There are many van services which leave from the airport for about $15 per person and will take you directly to your hotel. The van services
congregate in a group on the airport's second level -- one floor above the baggage claim at SFO. It's always a good idea to have your shuttle from the airport
booked before you land, since once you get there the van "barkers" will be overwhelming, trying to get you to use their service.
American Airporter is another service that offers pickup spots at liquor marts, etc, throughout the city, which can be convenient because you
can purchase tickets at the store before you board, and is nice if you're traveling with friends and you're staying at various locations.
But since shuttle operators are just as happy to pick you up at your door (for the same price), it seems like you might as well do that.
They'll go to any apartment, any hotel in the city, and they're on-call 24 hours a day. You can book online or over the phone - thereby limiting, again, the
need for excess cash!