If you live in the north bay and have a large group going to pier 35, and, if you can get your people together at one spot, Marin Airporter is the way to go. The cost is reasonable and they can take you INSIDE the pier, no dropping off at the curb like the limo's.
I have 33 people going on the Oct 22nd sailing and the bus will be at my house to pick up most of them and bring them to and from the city. The cost is only $20 PP, one way, including tip. Can't beat that. Call David Hughes at Marin Airporter and tell them Red Hill Travel sent you.