I don't have schedules in front of me, but when you add flight options from SFO, OAK and SJC, I believe Southwest has the majority of flight options.
Also, depending where in SF you're living, OAK isn't too hard to get to with direct BART connection. Given SFO's higher rate of weather delays, something to consider.
Also, also, Southwest has no-fee change policy, and you can refare if the fare you paid (cash or points) on that specific flight goes down. The difference goes into your RR account for future use within 1 year, I believe.
Keep us posted on what you find, will be interesting to know. Good luck.