Don McCall, The Boing Company writes...
Hard to beat Friday Harbor, in the San Juan Islands (45 minutes NW of Seattle, more or less). Half mile walk to town from the airstrip, lots of great little shops (many local artists and craftspeople live in the San Juans), couple of decent restaurants (some with a nice view of the local harbor and Cascade Mountains), and a very interesting (though small) whale museum and exhibit centered around the local population of orcas. Accessible only by ferry, airplane, or boat, so not usually TOO busy, but the place really closes down in the evenings so early weekday arrivals are best.
If you spend a whole day there, rent a moped or a bicycle (or 2, or 3) and see the whole island; lots of scenic areas, and if you spend a few hours at Lime Kiln State Park on the west side of the island, you have a fair chance of seeing a pod of orcas offshore; the water is very deep there, and I've seen them feeding withing 25 yards of the shoreline!
If you time your departure for about 30 minutes before sunset, an added bonus as you cruise around the islands is a wonderful (weather permitting) sunset over Puget Sound and the Olympic Mountains (assuming you're headed towards Seattle then).