If you have a little time, I can second the suggestion to take the ferry to the San Juan islands.
In the city, the Pike Place Market down by the waterfront is a great place to visit, and they have myriad food choices, including tons of fresh and healthy seafood.
http://pikeplacemarket.org/
I did Pike Place market, that was fun, but I didn't find time for San Juan Islands - makes me wish I had now two of your are recommending it. Maybe another time!