Visit Seattle [1], the Eastside, and the Puget Sound [2].
Add a trip to Mount Rainier [3] and Mount St. Helens [4].
Drive the Olympic Peninsula and Coast [5], then drive the Columbia River Gorge to the wine country [6].
Add a trip to Eastern Washington, stopping in Spokane [7] and the Grand Coulee Dam. Drive the North Cascades Highway [8]. Spend a weekend in the San Juan Islands [9].
Links:
[1] http://www.moon.com/destinations/washington/seattle
[2] http://www.moon.com/destinations/washington/north-puget-sound
[3] http://www.moon.com/destinations/washington/south-cascades/mount-rainier-national-park
[4] http://www.moon.com/destinations/washington/south-cascades/mount-st-helens-national-volcanic-monument
[5] http://www.moon.com/destinations/washington/olympic-peninsula-and-the-coast
[6] http://www.moon.com/destinations/washington/columbia-gorge-and-wine-country
[7] http://www.moon.com/destinations/washington/spokane
[8] http://www.moon.com/destinations/washington/north-cascades/north-cascades-highway
[9] http://www.moon.com/destinations/washington/san-juan-islands