The Fremont Troll (http://fremont.com/about/fremonttroll-html/
The International District (kinda sketchy, but they have great authentic asian food and bubble tea!!! Also the HI Hostel is down there...better than the Green Tortoise and close to the Amtrak station and the lightrail to the airport, as well busses to downtown)
Olympic Sculpture Park (http://www.seattleartmuseum.org/visit/osp/
Gasworks Park (I think that's the name...it's on Lake Union)
Ferry to Bainbridge Island for the day (never done, but lots of ATers like to do this trip during the RTR weekend)
As far as food goes...I like Local 360 and any of the numerous coffee shops that are NOT Starbucks (sorry, I just don't like the hoopla...I do drink it when there are no other options). Check out Mighty O Donuts, Top Pot Donuts, Molly Moon's Ice Cream, Cup Cake Royale....and the pierogi shop at the Pike Street Market...and Beechers too for some Mac N' Cheese.
The hottest places in hell are reserved for those who in times of great moral crises maintain their neutrality. -Dante Alighieri