I'm gonna through in a couple suggestions from my POV, take em or leave em.
What about having a meet-up outside of San Fran proper? Say, somewhere east of the Bay Bridge? This would allow folks (like me) travelling from other areas the opportunity to avoid going into the city, thus saving time, money and (for those not used to driving in San Fran) the difficulty of negotiating the streets in the city. This would also open things up from a parking POV. Sausalito is fantastic, love it there, lots of good food, but if memory serves, parking ain't easy. I typically park in one of the pay lots while I am there. During the summer, as many times as I have been there Sausalito has been a mob scene pretty much. Either way, still a great place to eat and enjoy the weather.
I think I could potentially come over for the day of the meet, but in all honesty, I hope that the number of folks will be at least 5 or more. No offense, small meet-ups are fun, but for me, the 4 hour drive over the hill and over to the north side of the Golden Gate might just be enough for me to not come, that is, unless the gathering is big, which makes it more worth while in my opinion.
So anyway, knowing San Fran and the surrounding area, I guess I am just thinking maybe this meet up will have more sucess if it is located in a more central, easy to access, less crowded area of the East Bay. There are plenty of nice State Parks which would make for fantastic, easy photo shoot locations (ex. Mt. Diablo). And the food is good pretty much everywhere in Northern California, so finding a good lunch spot to meet at shouldn't be too hard.
Anyway, I'm hoping to make it over either way, still don't quite know yet, but I just thought I would throw this out there.
Bart