Good to hear a few meetups are taking place!
I'll actually be in SF for two days (28/29 September), before heading down to Palo Alto for a conference.
I've been to SF before and loved it, but hoping to check out / revisit the following:
Golden Gate Park - loved this the last time I was here, Japanese Garden was excellent
Presidio - looks substantially larger than GG Park, so a bit unsure about this
Dear Mom - Not too far from my hotel, so will definitely check it out
Computer History Museum - This is where my conference takes place, so free visit!
Exploratorium - supposed to a lot like Launch Pad from the Science Museum here in London, and that is great.