http://www.citypass.com/seattle
There is also the Freemont Troll, which is an amusing little side-of-the-road stop.
Where to stay will depend on how high class a place you want to stay in. Myself, when I was last in Seattle, I simply wanted a bed to sleep in at night, so a Motel 6 in SeaTac was fine for me. Easy access from there into any part of Seattle