Reporting back..it was an easy walk to the Avis rental location on Hornby, and our total bill was $52 USD including taxes (and we didn't need to top the tank up, it was still on "F"). We visited Stanley Park (with a walk along Lost Lagoon), Spanish Banks Beach, drove around to the UBC and went to the Museum of Anthropology where we had lunch, and also found street parking near Nitobe Gardens. It took a while to get to the airport but it all worked out fine and we weren't tied to a tour schedule. We also had a snack at a Tim Horton's, figuring we deserved donuts after the wait in lines. The very friendly cashier was kind enough to take my old $2 Canadian bills, too.

Sounds like you had a really good day! Glad to see it all worked out.