Originally Posted by
number_6
$500 for drop-off seems like a good price -- whenever I have looked at one-way between Canada-US it has been $800 drop-off charge with Hertz and Avis (haven't checked Dollar). Remeber that Canadian car cannot be rented in US without special insurance (which some cars might have), so the car company probably has to trailer the car back across the border. Drop-off charges within US will be cheaper generally, so a one-way after you cross the border is an option but probably too inconvenient.
It may be more inconvenient, but to save several hundred dollars, it looks like it would be possible to take the train or bus to Bellingham, rent from Hertz or Budget there (Hertz is downtown, a 3-mile cab ride, and Budget is at the airport, a 10-mile cab ride), and then do your one-way to SEA for a LOT less money than from YVR. A test booking for a 5-day rental in August returns $384 all-in with Budget and $508.50 all-in for Hertz.
Honestly, I'd say there's not a ton in the short distance between YVR and SEA that's worth $500 to have your own car from YVR, and even the cost from BLI is pushing it. For what there is to see north of Seattle, it would be much more cost-effective to just take the train all the way to SEA and rent a car there and drive back north. You're only going out of your way 100 or so miles to save hundreds of dollars. Besides, the train is actually more scenic than the drive, since it's right along the coast most of the time, whereas the freeway (and even side roads) are mostly inland a bit. Honestly, unless you want to turn inland and make North Cascades National Park part of your itinerary or want to go out on the San Juan Islands, I'm not really sure where you plan on "stopping off midway through [y]our drive"...