Since you didn't get much response I'll give you one that isn't that close to Seattle, but you can do it. Head toward Ellensburg and take the Yakima River canyon to Yakima. It's probably the best road in Washington to drive, especially with the windows down because the sound echo's off the canyon wall. Plus the view is amazing.
Here's a google maps URL
Just look at the section of road on Google Maps, all twisty and stuff. Super fun road. Then you can drive it back, grab dinner in Ellensburg and head home.
EDIT:
Take a look at the google earth view of this stretch and you'll start to get an idea of why it's unique.