Alright, I spent over 6 years in radio so I can answer the question about the floors with the microwave dishes in Willis Tower.
Let's look at this picture of mine for a recent example here taken this past Spring.
The city of Chicago uses some of that space for relays within the cities (metro area) EMA, Public Services, and whatever. Those dishes provide "Line of Sight" to other towers in the area that serve as a repeater station. Essentially, it blankets the area with radio frequencies used by municpalities. Also, some of the dishes act as what's called "STL Antenneas". When a radio station has their broadcast towers off site, as is the case in Chicago, they have to have a way to get the signal from the station to the tower. They utilize a small transmitter at the station that "shoots" the music or talk signal from the "STL Tower" (with a dish identical to the ones on the upper floors of Willis) to the Transmitter on the 100, 101, and 102nd floors of Willis Tower. The transmitters for the radio stations in Chicago are located on these floors. Also located up there are the transmitters for the TV stations that rent space on the roof antenneas of Willis. The radio transmitters are not large at all, but they usually have two or three in case of backup. The TV transmitters on the otherhand are massive. These can easily take up a third of the floor space up there and require quite a bit of cooling as well. Most TV stations kept their "old" analog tv transmitters in case they needed them, so that's even more space.
Now, since I covered the whole transmitter debate here I want to add this as well. All these transmitters and repeaters are maintained by the stations engineers. These guys typically work two or three shifts and have work "stations" or work "shops" near their rented floor space where their transmitters are located. They have to be able to repair and service the systems when they go down so aside from their own personal offices up there, they will have a dedicated "work shop" for work on the antenneas and the transmitters. These floors are only accessible by special security clearance and keys and the roof of Willis Tower is only open to them on Monday's and Tuesday's for security and insurance reasons. This means there is usually ALOT of work going on up there at any given point. I hope this helps explain what these floors are used for.
And yes, a microwave dish and STL dish can work with a payne of glass in front of them. That doesn't affect the signal whatsoever.
The "Building" that is on the roof of Willis Tower is a mechanical house for the elevators and boilers that are on the floors directly below them. Access to that is through a couple of doors or a hatch in the actual roof of the tower (the hatch opens up to the penthouse floor).
FWIW, this is the 99th floor, or the "Backup Skydeck". I have been to both the 99th and the 103rd (and walked out on the "Ledges" too) so I got a taste of both.
Sorry for any spelling mistakes. It's late and i'm dreadfully tired tonight.
Here are a couple of shots from my upcoming thread on Chicago!!!
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