Have a great trip. That's going to be a cool drive through the northwest. Wait till you see the Redwood Forest! If you have time in Seattle, go see the Experience Music Project. I see now it's also a Science Fiction Museum, but it's supposed to be pretty cool. We never quite got to it when we lived out there in Portland, although we did go see the IMAX of Mt. St. Helens erupting. Whoa.
http://www.empsfm.org/
I'm so jealous. It's BEAUTIFUL out there. Great mountains, great big fir trees, beautiful beaches with trees right up to the edge of the water (and exceptional shopping)! Report back!!!