We booked an Alaskan cruise for next summer. I'm so crazy excited....

BUT, we are trying to keep travel costs down so we can spend a little more on excursions. We have a Southwest VISA, and we have a ton of points, but I am not sure if/how we could get from Seattle to Vancouver in the most cost effective way. Is it possible to rent a car and cross the border?

Does anyone have any suggestions on a Chicago-to-Vancouver route?