In Seattle, for reasonably priced shellfish in a casual setting, Taylor Shellfish (multiple locations).
For more upscale and a very wide array of local produce, seafood etc, Lark. A bit expensive but absolutely worth a spulrge.
Eater.com has a bunch of other recent recommendations.
http://seattle.eater.com/maps/best-seattle-restaurants-38
http://seattle.eater.com/maps/best-new-seattle-restaurants-heatmap
Edited to add-
I just realized that I had already recommended these two restaurants in a Seattle-dedicated thread that someone else had created. At least I am consistent!
Two more recommendations from my husband who just travelled there a few weeks ago.
Matt's in the Market (Pike's Market)