My husband and I rented a go-car to do a GPS guided tour of the city. You wear a helmet and they run you through a safety and operating video before you go. It kind of runs like a motorcycle.
I'm sure the locals find it annoying as you are in this mini vehicle on the road with all the normal cars, but that kind of makes it more hilarious.
I feel like we really saw the city by doing this, that we would probably not have seen otherwise.
If you are thinking of doing this take the longest tour you can. We went all down the piers, all the way from the bay bridge to the golden gate bridge. We went on regular streets with houses, by a beach, down the hilly and windy roads, through the financial district, in some parks, chinatown etc.
I was a little scared of being on the road with the big cars and my husband was driving a little fast for my liking but it all ended up being such a cool and amazing thing to do.
Once in a lifetime experience - especially if you don't have tons of time in the city this was a great way to see so much.