You could go to the touristy parts or could try to hook up with locals who know the real good food spots ;P. Here's some you may want to look up.
Salumi's - good luck getting a sandwich w/o a line only open for lunch Downtown Seattle
Judy Fu's - Homemade Noodles ftw! North Seattle
Szechuan 99 - Extremely good Chinese food outside of Chinatown.
El Gaucho's - Great Steaks here as well Downtown Seattle
Those are a few of my favs heh
I'll try to name more obscure and/or unnamed spots in Western Washington.
Could also go check out the Frank Gehry designed EMP. Ballard Locks, The Fremont Troll, Olympic Sculpture Park, Museum of Flight, Pacific Science Center(basically Seattle Center), Seattle Art Museum, if it were warmer i'd say give the
Ducks a shot lol