Take a ferry or boat ride around the harbor or nearby island (Bremerton, Kingston), Kayak on Lake Union if weather permits, Ride a sight-seeing seaplane with Kenmore air
Skiing at Stevens Pass
Go to Washington Park in Anacortes, WA and walk around there. Hit Deception Pass on the way there.
Chihully Gardens – Argossy / Harbor Cruise – Bill and Melinda Gates Foundation discovery center – Museum of Pop Culture (museum adjacent to Chihully gardens) – Tulip festival in Skaggit (40 miles north – impressive tulips in April)
Hiking from Paraside Base on Mt. Rainier, Mt. St. Helens, Ferry to Bainbridge Island, Flying Heritage Collection (WWII Airplane Museum) in Everett