Nothing within walking distance, but we have an awesome bus system.
Take a bus to downtown, there's plenty to do there in 10 hours, we have an awesome aquarium down on the water front, some cool shops down there, good restaurants, Pike Place Market is just up from there, Seattle Center, the Science Center, Imax, Space Needle, Belltown for bars, etc. You can walk all over downtown, everything's pretty close.
Go to transit.metrokc.gov to look for busses, it has a very good trip planner to help you out.