Posted September 13th, 2017, 10:10 AM
Pile place market, Seattle Center and the Space Needle, museum of flight is also fun. You could take a ferry ride to Bremerton or Bainbridge Island. Klondike National historic site is cool as well. Lots to see and do and it depends on you budget and interest level.
Be aware that the ferry system has really struggled this summer. They have 22 boats, need 19 to operate the summer schedule, and spent weeks with at best 18 boats working. One of the two boats on the Bremerton run has engine problems, so they're just running it on one engine until they can get enough other boats back in service to finally take this one off the run yet keep two boats on it (it's the longest run at 60 minutes of all the WSF trips except perhaps the inter-islands run up north). However, it's running a lot slower, so they've totally doctored up the schedule as a result. If you're looking for a slow, peaceful ride, seek out the Kaleetan.
If you're into flight and have transportation, head north of Seattle to Everett (actually Mukilteo) and do the Boeing Factory Tour. It's about $25pp (seasonal pricing, discounts, etc. may influence the price), lasts 90 minutes plus free time in a "micro-museum" and/or outdoor viewing area, and gives you a high-level view of building 747s, 777s, and 787s, with a tiny glimpse of where they build 767s.
Repositioning Ruby Princess (VAN-SEA) 5/5/17-5/6/17
Mexican Riviera (LA RT) Ruby Princess 2/11/17-2/18/17
Repositioning Crown Princess (SEA-VAN) 9/19/15-9/20/15
Alaska (Seattle RT) Ruby Princess 8/9/15-8/16/15
Alaska Sampler (YVR-KTN-SEA) Ruby Princess 4/29/15-5/3/15
Alaska (Seattle RT) Grand Princess 7/20-27/14
Alaska Northbound Sapphire Princess 8/11-18/12
Alaska Northbound Coral Princess 9/4-11/10