If you're in the south Seattle/SeaTac Airport area, check out A Place for Pets on SW 152nd in Burien. They just opened a few months ago, and at least one of the owners and some of the staff are fishkeepers. I've had very good luck with their fish, and their plants have been much better since they switched suppliers, although I still get most of my plants from the 'net.
if you want to look them up.
Oh, and welcome to Seattle!