I'm limited because I work for a contractor and have to respect confidentiality, and generally shouldn't talk about other firms. Also I don't do pics. And this thread is about highrises only. But generally, in a "greater Downtown" area of about 2,000 acres:
Transit includes (a) a light rail tunnel underway from Downtown for three miles to Capitol Hill and the University of Washington (extending our existing single LR line), and (b) a new streetcar underway from around Union Station to First Hill and Capitol Hill. Also King Street Station, used by Amtrak and commuter rail, is getting a sizeable historic restoration.
Office construction currently includes a scattering of small building on the Downtown peripheries, four that I can think of (a fifth, for Amazon, just opened). Demo is about to start for a 38(?) story, 1.1 msf tower for Amazon, the first of three similar towers, which will take their HQ past 6 msf. Developers will start another 600,000 sf or so in the next month in two lowrise (six stories or so) buildings in the South Lake Union area. South Lake Union has a handful of other proposed projects planned, often at 12 stories and 160'. A variety of other projects are planned, including sizeable towers, but they haven't announced plans for anytime soon.
Hotels are lining up and should start starting this year. The 10-month occupancy rate was 80% through October and room rates have been rising, so it's time. We also just closed 200 of our 12,000 Downtown rooms for demo for the first Amazon tower.
We've been having periodic housing booms since 1980-1982. The current one has totaled 8,000 units started since 2010. That might be a bit more than the 2005-2010 boom, and it's way above the three before that. That includes projects now underway of 40, 40, 39, 27, 25, 25, 24, 24, 24, 13, 10, and 10 stories, with the other half of the current projects being woodframe. (That's counting a project that's currently shoring in advance of excavation, so being pretty liberal.) Completions in the current boom peak at 17, 16, and 16 stories. Going forward, a similar number is in the short-term planning stages. That doesn't include master planned stuff, particularly the reconstruction of the Yesler Terrace public housing complex on First Hill, which will replace about 550 units with 3,000 to 5,000 over at least a decade aided by a private developer now being chosen.
The laboratory sector is pretty slow. One building is underway, an addition to the University of Washington's satellite lab complex (the UW is perennially the #1 public university in NIH grants).
The hospital sector is also slow. Greater Downtown has three major hospitals, and all have recently finished buildings (past few years), but none have anything major underway.
On the highway front, we're currently building a 9,000-foot deep-bore tunnel for Highway 99 to bypass Downtown. This is in the early stages (digging the pit for the giant boring machine, which will be shipped soon) and will open in three years. This will allow us to get rid of our current Elliott Bay waterfront viaduct and an existing six-block tunnel, and reconnect three blocks that are currently cut in half by a surface portion of 99 in the South Lake Union area.
Related to the waterfront, we're building a $200m seawall fix. After that, and after the viaduct is gone, we have a lot of roadwork and public space to build, similar to San Francisco's Embarcadero. The new surface road will take much of the "local" portion of the viaduct's current traffic. Another related project is redoing the Mercer/Broad/Valley area in South Lake Union and Lower Queen Anne, one outcome of which will be a much smaller volume of traffic along the lake, knitting neighborhoods back together, and providing a direct (vs. convoluted) westbound traffic route. Phase II (out of II) starts this month or next.
Two museums have opened in the past six months. One is the Chihuly Gardens and Glass, next to the Space Needle. The other is the relocated Museum of History & Industry in a historic building on a pier over Lake Union. Another museum, the Experience Music Project / Science Fiction Museum (a combo) is building one of the four office buildings I counted.
If we get an NBA team, we could start an arena, which I'd guess is a year out.
On the retail front, a new City Target just opened at 102,000 sf, of which maybe 80% is the store itself. Otherwise no major projects in the past year. Well, one...the Pike Place Market finished the last phase of its renovations, which covered a few city blocks. They plan a parking garage and more retail and public space overlooking the waterfront, which might be a year away from starting.
Edit: I forgot colleges. City University of Seattle is moving from the suburbs and opens this month in the Belltown neighborhood. Northeastern University opens a small office in South Lake Union also this month. Was reminded by a headline. Seattle University has big plans, particularly on the housing front, but nothing major currently. Seattle Central Community College isn't building. On the downside, the Art Institute of Seattle might move outside Downtown.