Hey, everyone.
Here's a list of airport shuttle bus options:
http://www.san.org/airport/ground_transportation/shuttle_services.asp
There are usually several shuttles waiting at the airport. (Cloud9 is
one of the better ones.)
From Terminal 1, you must cross the skybridge, and take either the
escalators or the elevators to street level.
From Terminal 2, cross the Terminal 2 skybridge and take either the
escalators or the elevators to street level, or use the pedestrian
crosswalk conveniently located outside the Terminal 2 baggage claim
area to access the transportation plaza.
An attendant will place you with the first available shuttle, unless
you specify a particular shuttle company. Expect to pay around $30 for
the first person and $10 for each additional person.
-- Patrick