A car will make things easier, but Vancouver traffic seems to get busier with each passing year. Expect to spend a lot of time stuck in traffic, particularly downtown, heading across the Lions Gate Bridge, approaching the Stanley Park Causeway...you get the idea.
Gastown is an easy walk from many downtown hotels, and Granville Island can be accessed by small water taxis like the AquaBus from both Yaletown and the West End. Parking on Granville Island can be quite the challenge; take the water taxi over for a few bucks and save yourself the stress.
Having said that, a ca