I don't want to rent a car because I don't like driving. However, as long as people are cool with hopefully short drives to the Caltrain to pick me up / drop me off, we should be good.
So, from the tentative plan described, I'll take the Caltrain to Berkeley on Saturday... which... doesn't exist, that's BART again. Goddamnit. Well, we'll see if I can hitch a ride or just take a taxi over there. Afterward, depends on what the plans are; going back to the Valley + taking Caltrain back to SF works, as does briefly going into San Francisco so long as it's not an insanely long walk back to my hotel. (As expensive as a taxi is, it's still cheaper then renting a car + garage fees.)
Sunday should be easier; I'll just take Caltrain into Sunnyvale or wherever else people are meeting up, and can be picked up there.