LaLaLa: I have park and flyed from the Hampton Inn PDX. Seemed that the last time we did it, it cost $10 per week, so the total stay including parking just about equalled parking only. You park in the unpaved area next to Hampton.
Just to chime in on the discussion re: where to stay. If you want to eat at decent restaurants, downtown or Lloyd center are probably best. This leaves one with a Doubletree at Lloyd Center (yes it is an old Red Lion, but the public areas, at least, have been renovated in the last decade. The new Hilton Towers is the newest facility downtown. Doubletree is out of the way and fairly inconvenient though technically still in downtown. Embassy Suites is newer and covered by various threads.
Airport has an ES, the Hampton (next to the Sheraton) and the HGI.
The three or four DoubleTrees on the Columbia at Jantzen Beach and across the River in Vancouver are all old Red Lions. At least one has a good restaurant. You definitely need a car for these and possibly a car for the airport locations unless you are a mickey D fan.