Chicago to the Pacific Northwest RoadTrip

[snert]

My wife and I are looking for ideas for our 3-4 week road trip from Chicago to the Pacific Northwest in August 2006. I have the IL bar exam during the last week in July, but I don't start work until after Labor Day, so we might have as much as a month. We definitely want to hit Seattle, Portland, and have friends in Bend. We plan on buying a Nat'l Park pass and seeing Olympic, Mt. St. Helens, and Rainier. We plan on alternating between camping and staying in hotels/B&Bs.

It seems that I-90 is the best way to get out there, but we're open to suggestions. I'd like to take a different route back, just for variety. If its scenic enough, we're also into staying off the interstate for a while. Any ideas on suggested routes, or places not to miss on the way out/back?