Welcome. Most of the event activity is based in SF. There are fewer events on the peninsula. Mtn. View is kind of boring by itself (not much to do after 10pm even on the weekends) and the social scene is based around established friends networks, dinners, and movies. SF has a mix of real startup folks and some 'tech hipsters' (tech folk trying desperately to think they're no longer the high-school geeks they really are). You'll find it easier to network and attend events in SF.

So, try landing in SF first. When you're actually ready to start something, I might suggest revisiting the south bay. The lack of social events is actually a huge plus for getting work done. Plus the engineers you find in the south bay tend to love their work more (not as interested in the 6pm happy hr).

Feel free to ping me when you get settled in (I'll leave an email hint in my profile).