I know exactly where you are coming from: a few years ago I decided I was going to move to either SF or NYC from socal. I interviewed at a bunch of places and spent time socializing in both cities, e.g. going to parties, meeting friends of friends, etc. It was an involved decision that I made carefully.

In the end, NYC was a no-brainer for me. I consistently found the bay area has developed an homogenous culture that even pervaded my non-tech friends' lives. People always asked the dreaded "so, what do you do?" way earlier than they did in NYC. And unlike in NYC, I often felt like I was being judged for my answer. I hated this because I like a strong work-life seperation. In NYC I found there's less of a social "hierarchy" based on profession. At a typical party you can meet an artist, an actor, a doctor, a hedge fund investor, and a marketing executive, and all may kick ass at their jobs. I got exposed to an insane amount of culture in NYC that I didn't see in SF.

Keep in mind that this is written from the perspective of a professional - there are probably large parts of the two cities that culturally overlap. Also, I'm not trying to say SF is a bad city, but it isn't for everyone.