Just came back from a trip to Washington and have to say that I tasted some excellent wine at some local wineries. I would suggest you take a look at Bookwalter, DiSteffano among others. The people there were extremely nice and there was no attitude like you get at some Napa wineries.
Hm, Bookwalter is down the street, I'm on their "twice a year plan".
If you're in the Woodinville area, you should also check out DeLille.
If you're out around Prosser (which you should do on a weekend sometime) check out Terra Blanca and Hedges.