The airport code for San Francisco International Airport is SFO.
A flight comparison site such as Hipmunk is recommended to get an idea of the prices on several airlines (most sites don’t include Southwest Airlines, by the way). You can also set up a fare alert from Airfare Watchdog, which will let you know when there’s a good fare to San Francisco.
AMERICAN AIRLINES — 5 percent off
Travel dates valid: April 22 – May 1, 2013
Travel to San Francisco or San Jose, Calif.
Tickets can be purchased at AA.com