Welcome aboard the RoadTrip America Forums!

Your general plan seems workable, and there is certainly no shortage of things to see. If you can handle that much mountain driving, by all means go for it. You will be breaking it up every so often with stays in more level surroundings such as Yellowstone. A couple of things to plan on seeing and doing on your trip. I'd make sure to stop and visit the Grand Coulee Dam. If you call ahead, you might even be able to schedule a tour.

Heading north from Yellowstone, you should at least plan on a drive across Going to the Sun Road in Glacier National Park and then using the Crowsnest Highway across southern Alberta and British Columbia. If you remember the movie Roxanne with Steve Martin and Daryl Hannah, that was filmed on location in Nelson, BC.

Finally, while I liked Vancouver, I much preferred Victoria, the provincial capital, on Vancouver Island, Look into taking the ferry over, poking around the gardens and museums, and then returning to Washington by ferry from Victoria to Port Angeles.

I do think you may be setting yourself up for information overload by trying to see everything. You simply can't cover it all or even most of it in three weeks. Many people who do too much research end up regretting that they couldn't get to everything they wanted to see rather than reveling in all the things they did get to see and do.

AZBuck