I took the commuter ferry from Tiburon to San Francisco, then did the 9 hour extended tour with San Francisco Shuttle Tour (http://www.sanfranshuttletours.com/), I would recommend them. It was a nice tour, lots of getting off the bus to actually see things. The poor guide though, can you imagine guiding 40 tourists through a city? I’m sure he doesn’t get paid enough.
Anyway, nice tour, hit most of the famous parts of SF:
Driving: 0 miles
Walking: 18,210 steps