Gardening books and forums all suggest contacting your local cooperative extension for lists of native plants. Washington State University seems to be the most widely publicized for Washington State. However I'm finding King County's website to be far more useful.

http://green.kingcounty.gov/gonative/Index.aspx

Here is why.

King County's site has about a dozen planting plans for Seattle by microclimate, ranging from dry and sunny to wet and shady. The plant lists are very detailed, and name the settings that work best for that particular plant, size at maturity, evergreen or deciduous, easy to find, etc., and there are photos of all of them. There's lots of other useful information too. It's thorough, very well organized, and cross-linked. A real pleasure to navigate too.

What makes this site priceless to me is that the planting plans are scaled! I finally have a clue about what mix of evergreen and deciduous plants I'm putting in my backyard and where. My previous research gave plant heights only, you see.

Here is a link that might be useful: Native Plant Guide, King County, Washington