Oregon

Depends on what your definition of "best" is. We took nearly the same route in 2011 on our way to Corvallis. On the way west we took the northern route on I-90 through Spokane and Portland. For the most part it was a good road and reasonably scenic. I can't say I'm a fan of the Portland traffic, though. There were some significant downgrades on the west side of the mountains, but my exhaust brake handled them pretty easily with very little assistance from the service brakes. For our return route we took U.S. 20 towards Ontario, ID. Though a pretty good road, it's two lane and sometimes, I thought, a bit narrow. East of Burns, OR. there are a couple of mountain passes to go through. Again, it was a good road, but a bit narrow in places. There is a really nice campground towards the east end of Burns and a really good steakhouse in town. (Sorry, I can't remember the name of either one.) There's also a really good diesel repair shop on the west end of town. (I'd rather not expand on that, please.) The east side of Oregon is not very scenic unless you're really interested in prairie ground or hay, onion, and potato fields. It was nice for us to see it once, but... Hope this helps.