No particular order. Please don't take too seriously.
San Francisco - 345 California Center
Considering this was designed by Skidmore, Owings & Merrill, who have made some of the greatest buildings in the world, these "Tweezer Towers" are a gaudy embarrassment to everyone involved. Between the juvenile ambition of the double spires and the confusing angles, I can't precisely say what makes this building so hideous. It essentially looks like an ugly, downtown hospital from the Wizard of Oz. Ironically, the height restrictions of the time prevented an even greater tragedy.
San Francisco - California Automobile Association Building
Even if the people inside are happy and well-paid, I still wouldn't admit to working in it simply because it's so shamefully ugly. What a dreadful, soul-crushing concrete box with a design "efficiency" that would make a Moscow housing project look like the Bellagio. Also, San Francisco has a surprising amount of these depressing, modernistic "grid buildings" and has easily the most overrated skyline.
Charlotte - Bank of America Corporate Center
Another boring, obvious early 90's design that leaves you feeling empty. Its "puffy" stance and lack of repetition breaks feels like they were compensating for something. So in the end, the largest building downtown is the least interesting, and least popular. The locals mockingly call this building the "Taj McColl" after the massive ego who built this evil empire headquarters. And just how un-American is it to have 60 floors to pay tribute to the Queen of England 60-year reign?
Atlanta - Coca-Cola headquarters
The panels don't really match up, the viewing angles must look dreadful from the corner offices; esteemed dreadful box design, and the most useless spire "thing" I've ever seen. The closer you look at this failure of human engineering, the more ashamed you are of being one. For a company that supposedly had its roots in great Americana design; where is the evidence? Oh wait, we're talking about a hangover remedy with cocaine inside.
New Orleans - One Shell Square
The worst part about this building is that almost the exact same thing was built only a year earlier in Houston. Big, empty corporations usually make big, empty-feeling office building designs. New Orleans has an otherwise, subtle, old-fashioned downtown and this building smears 80's boxy feces all over it. Maybe them not cleaning the exterior properly is supposed to make it blend in more. Looking at it inspires such emotions as "pointlessness" and "cage".
New Orleans - Sheraton New Orleans
Seriously, I wouldn't even take a hooker to a place like this. It looks like a patch-worked cardboard box with plexi-glass. I don't understand why there are random breaks in the window pattern. If that was supposed to be a design characteristic then it's completely over my head. It just looks like they are patching up bombing attacks or something. The official website over-saturates every photo to make it look more colorful than a hallucination at Circus-Circus.
Dallas - Mercantile National Bank Building
I can't imagine that in the 1940's, they'd make a building that tall and that plain. I can see why Dallas has been a hotbed for con men because just looking at the building crushes all optimism and faith in society. Nobody was ever happy with anything about this place as it was remodeled more times than anyone bothers to remember. The clock is stupid and its stance makes it look shorter and smaller than it actually is. This would be considered a bad lego building design, let alone an actual one.
Dallas - Elm Place
Sporting the 1960's audio-receiver look, the architect of the Cotton Bown stadium taught the world how to make a box look more like a box with panel manipulation. Where is the ambition? Or did that money go into furnishing the horse ranch? Texans probably actually like this design because they like anything that lights up like strip joints at night.
Dallas - Trammell Crow Center
Dallas, AGAIN! It looks like some mechanical object that needs to be fitted in a factory machine. Which, I imagine, was the inspiration. The building looks petrified in the 80's. The downtown would look more modern if the Trammell Crow Center was replaced with an outdoor flee market. The strange Freemason references (glass pyramid, geometry), only convince me more of its pretentiousness. Its 1984 time capsule (to be opened in 2084) will be the greatest non-event ever.
Fort Worth - Burnett Plaza
Not to forget Dallas' neighbor! Fort Worth really had to make a lot of modern glass buildings to compensate for this concrete abomination. The messed up elevator shafts and tight "cage grid" design might convince a naive passerby that this is actually a city jail. Try it!
Houston - Four Leaf Towers
I don't understand why people ever hired Cesar Pelli to design anything. Almost everything he made was dreadful. The Petronas Twin Tower are terrible, and my favorite, Bank of America Center in Charlotte is a travesty. Everything he's ever done has either been gaudy or plain obvious. Guess of which "design ambition" he employed on the Four Leaf Towers (two of them (...?)).
Houston - Devon Energy Tower
Don't let the link's diagram confuse you, it really does look like a rabbit cage. The name of this place is ironic really considering no energy was put into its conception. I can't find any solid data on the architects.
Houston - Continental Center I
This post-modern gas chamber inspires suicide and nothingness at every section. Everything looks sterile and as if designed to trap people inside. Sort of ironic considering the only thing this building was known for was being vacant.
Los Angeles - U.S. Bank Tower
The centerpoint of Los Angeles is really quite embarrassing to anyone who's been to a Chicago or NYC. The final verdict; the tower has an immense lack of imagination (where ARE you Hollywood?). The architect firm, who made a career of making non-serious buildings for non-serious people, were inspired by the shape of a car transmission as the crowning achievement of the most illustrious city in the world. The obviously-late 80's endless-pastel-nightmare color scheme will trap the LA skyline in that decade forever. This is a dreadful building and an eyesore to the gods of the San Andreas fault. I can see why they blew it up in the film Independence Day!
Los Angeles - 777 Tower
My favorite architect Cesar Pelli strikes back with another painful, late 80's pastel rabbit cage. The pointless sectioning and that dreaded bloated shape will never look modern again. But it must take a true visionary not to see that... or something. The politics of Pelli somehow gave this 10-minute, postmodern, curtain wall design awards for years to come.
Denver - Brooks Tower
Denver has the worst skyline in the nation. Only a few places in supposed civilization would they ever build this tall, this ugly. I might be wrong but I think this building inspired the building-crunching arcade game Rampage.
Denver - Republic Plaza
You have GOT to be kidding me. Nobody ever grows up to be an architect to design something this plain. To take all this granite and to make it all into a perfect box is really kinda creepy. Is it me, or is every tower in Denver a copy of another tower somewhere else in the country? And to think who designed this... for shame!
Salt Lake City - Church Office Building
I didn't realize a church needed so much office space but then again I must be limited by my Catholic scope. It took them 10 years to build something that looks like a nuclear substation in eastern Siberia. I think I might have seen this exact same building in Fallout 3. Maybe I'm just being knee-jerk but I was expecting some stain glass or puritan architecture or SOMETHING. Come on, I think the architect was some sort of upstart. The whole Brigham Young family legacy "thing" makes me wanna barf...
Minneapolis - U.S. Bank Plaza
Another travertine Tron nightmare; this one looks quite cheap and stagnating from the sidewalk level. Maybe the idea was that they could make two buildings for the price of actually designing one. I know the idea was to bring out the elegance of windows by making it all simple, but instead, the windows look like those solar panels you see on crappy calculators.
Milwaukee - 411 East Wisconsin Center
It's amazing how ugly this looks compared to the rest of downtown. The shadow that dismal concrete box must create is not worth its office space. They bulldozed a wonderful relic called the Goldsmith building to build this jagged shard.
Detroit - One Woodward Avenue
Detroit's fantastic skyline was introduced to the dreadful 60's. If buildings are meant to inspire then it's no wonder cars from Detroit have become boxy and cheap. What works in Tokyo, clearly, doesn't wok in Michigan. Maybe I'm not qualified to say it, but why do I think that? Like Joe the Plumber, I have a mouth that can emit sound.
Buffalo - One HSBC Center
Losing TEN straight Superbowls can't be as bad as having THIS as your city's largest building. Holy cow, this wouldn't even be complex enough for a modern parking garage.
Troy (Michigan) - Top of Troy
I'm sorry to the humble folks of Troy. Whatever design contest or process you guys used was obviously the wrong one. The official website's poor quality would make me laugh even in the late 90's. The building's design was laughable by the late 70's. It desperately needs a new color theme and panels that actually match up.
Philadelphia - 1818 Market Street
What a terrible eyesore to Philadelphia's glass skyline. Real tough to find ANY pictures of it really. William Penn would at least be thankful it was built lower than his statue.
Pittsburgh - Fifth Avenue Place
Whatever idiotic geometrical ambition this building has, I don't want to hear about it. No stat or detail can make up for the ugliness and whimsical attitude this design employs. Pittsburg is a hard city with a no nonsense attitude. There isn't a more unfitting building in any city's skyline, even when they flood light the place to look like it came out of hell.
Las Vegas - Encore Las Vegas
This is how building's SHOULD have looked from the 70's. But this ain't the 70's, and the elegant, polished tape-deck look just doesn't cut it anymore. How utterly uninspiring and flat out pretentious and ghastly. Worst part is that Wynn built two of these idiotic monoliths. Who the heck would go to Vegas excited about staying at the Encore? I can think of ten I'd still rather go to.
Nashville - William R. Snodgrass Tennessee Tower
I'm not sure what kind of an honor is named after something so mundane. Only an insurance company can be that cheap with design. Figures the state government bought it to be used as a civil jail. And no, you CAN'T bring your gun inside, hillbilly.
Baltimore - Transamerica Tower
Designed by a guy that makes projects this special design cheats the inhabitants of corner offices or any sort of proper view. It also cheats the outside viewers of humanity. There's a banner at the ground level that inexplicably says "believe" perhaps as a suicide deterrent?
Chicago - One Magnificent Mile
You know it's bad when the main facade color is listed as "dark pink". Chicago is only next to New York City in the WORLD'S best skylines and pointing fun at ANY building from either of those cities is sacrilegious. HOWEVER, this building somehow won awards, I assume, for its gimmick of making everything idiotic hexagons. It's not that this pompous design has no place in the world, just not in Chicago world.
New York City - Sony Building
Sorry New York, but the Sony Tower is your eyesore. It's simultaneously pretentious and shockingly plain. Its brick-like facade just makes it look cheap, not nostalgic. Yes, I know the central arch is a throwback feature, and no, it doesn't make it cool at all. There are at least 10 things this building copies and not a single of it well. The skyscraper is supposed to be a tribute to NYC, but it is instead a criticism. Sort of like "you're cool, but in a kinda nerdy, tacky, not-too-serious way." This is New York City, not the Hard Rock Cafe.