We just made a similar trip, but slightly different. Took I90 over the 
Cascades and then US97 down to central Oregon. Entirely different 
landscape, sage and grasslands, basalt canyons, winding rivers. Stayed at a 
fabulous state park near Redmond Ore, Cove Palisades State Park. There were 
about a half dozen campers there, we had the place to ourselves. Went to 
Smith Rock which is a really neat place. Then drove over mountains to 
Newport and back up the coast.

-Mark McCulley