I'll spend a day riding the MAX light rail in Portland, and then probably take the Cascades to Seattle, rent a car, drive up to British Columbia and at least watch the Canadian come through Kamloops...
Will they let you cross the Border in a rented car? You might want to check on this. Otherwise, you could take the Train from Seattle to Vancouver, BC and THEN rent a car to visit Kamloops.
I'm assuming yes, because when I priced a rental car from Enterprise in Seattle, the fine print said I could drive the car within a several state/province area including Oregon, Washington, British Columbia, and several others I forget. Now, I suppose there's a distinction between "will Enterprise allow me to drive the car into Canada" and "will US border control allow it" and "will Canadian border control allow it".... Yes, worth looking into; I was assuming it would be cheaper to rent the car in Seattle than in Vancouver (and indeed, it was only $157 taxes included for a week, which seems like a good deal).
I'll give AAA a call; I'm assuming they're up on those sorts of details. Or is there a better resource?
--Will