Duluth, MN to Vancouver, BC in mid-March '05

Hey all. I'm planning to take a long road trip in mid-March (Springbreak) from Duluth,MN to Vancouver. This may include a night stopoff in Seattle as well. I'm looking for any suggestions for points of interest, as well as any route information other than the usual interstate route of 94 West and I-90 East. The route I have mapped is via yahoo maps and takes me from Fargo,ND thru Bismarck,ND and on to Billings,MT. This is where I change interstates from 94 to 90 heading westbound. 90 loosely passes Helena,MT and heads into Spokane,WA and then to Seattle. I'm sure there has to be some interesting things along this route that I don't want to miss- any tips or tidbits?

Personally, there are two routes in that neighborhood that I'd like to drive -- US2 -- and the Trans Canada Highway 1.
At least one direction, I'd use one of these two. I am not one that gets bored with Great Plains' vistas.

Along with the usual recommendations for the northern route (Badlands, Black Hills, Yellowstone, etc), I think Theodore Roosevelt Natl Park in North Dakota is worth a look, and I'd get off the main route and retrace some of the Lewis and Clark Trail -- next summer is the 200th anniversary of that particular part of their journey -- from Fort Mandan westward.

In March, you will encounter some road closures in the mountains of Montana and in the Cascades, so you'll need to do your homework before you go -- find out what's open and what isn't. You should be able to find plenty of info on that right here with the links provided on RTA. Most of the route is all-weather highway, however.