We decided to go on this tour while in San Francisco and it was well worth the money. I saw so many places while on this tour that I would have not seen otherwise. Grace Cathedral was amazing(http://www.judysbook.com/members/Jolene/posts/2006/11/485795/ ). The tour included a ferry ride and the whole tour took about six hours. I thought it was only going to be about three or four hours but the tour was so fun they kept us going. The best part was that our tour guide and driver were two different people. They served us soda's and water on the shuttle complimentary.
Jerry our guide was very informative and really seemed to know what he was talking about. He was able to show us the best possible places to take pictures and even took everyones pictures as a keepsake.
I highly recommend this tour.
Visit them at www.sfshuttletours.com