If you're staying downtown: Embassy Suites. Simply a great property. And you can walk/ride light rail/ride the streetcar to anything you'd be interested in.
If you don't mind the burbs: Hilton Vancouver. Even though I had a bad experience here (took 15 minutes to check me in at 4 a.m.). It's new and very convenient to I-5, which will get you to downtown Portland in 10-15 minutes if traffic is moving.
Looking for a bargain?: HGI in Lake Oswego or Beaverton. I've booked Beaverton in the past for as little as $55 with a AAA discount, even less with Net Direct rate (nonrefundable).
Enjoy the City of Roses!