It varies. I'm in East Bay, and we're going in November ... I'm flying Alaska on the way over from SJC to MCO, then on the return we're flying Southwest on the way back (also SJC). We got Alaska for $130/person, Southwest was closer to $150 but that Alaska rate wasn't available on my return date, and we had points to use.
Last year in December we flew Southwest both directions for about $170/person from OAK, again one way on points which is the main reason we went with them.
Generally OAK is my favorite airport, followed by SFO/SMF since SJC is the farthest/least convenient ... and usually OAK and SJC are comparably priced, but for my dates it turned out SJC was the winner by about $50/way/person, which adds up when you have 3 people and can get a ride to the airport (or park cheaply, haven't decided which yet).
Start hunting a ways out, a few months before Southwest/Jet Blue release their flights, then when you find a price you like, book it. Generally if I go Southwest I book on the first day, then wait to see if there are any sales so I can get a credit for future flights.