Yeah when i wend down last year we stayed basically down town near enough to a BART station. Then a few hours before the game we took the BART to Balboa Park. At Balboa park there are busses that run to the Stadium. They are fairly crowded. Also, after the game it's kind of a mess. I recommend that depending on the score you get out there early or you'll be waiting a while. Also ask the driver as you're getting on to make sure they are going back to Balboa Park. There was some confusion between where the drivers thought they were going, and the route they had on their bus last time.
Overall not a horrible experience but you have to be willing to deal with waiting and crowds just like any game. I also imagine you might be dealing with more hostile crowds than we did. Can't say the rivalry last year when i went down for the thursday night game was as heated as it is now. We didn't really get much grief. But after the way we've slapped them around the last couple games I imagine you might get more crap.
Anyhow if you want anymore info, PM me and I can probably give you a few tips based on where you're staying. Last year my cousin and myself went down, landed at SFO, used the bart to get down town and it was pretty easy to figure out getting around and getting to the game. Fun city to hang out in.
Some things I found helpful:
-Map of SFO - like this one
http://www.mappery.com/maps/San-Francis ... mthumb.jpg Useful so you can know in advance how to get to the BART station at the airport.
-Map of the area around your airport and it's location to the nearest BART station
-Map of the BART lines - they are up all over the terminals but they are useful to look at in advance so you know what to expect.
-Schedule & bus information for balboa park busses. 75x is the route we took.
It's a fun trip. Would have been 10x more enjoyable for us if we had won and would consider doing the trip again this year if not for the timing of the game this time.