I was in NYC over the weekend and Los Angeles - for my first time - back in April. Both large cities with large populations. Both trips were for mostly pleasure. In NYC I stayed in Williamsburg; in LA I stayed in Silver Lake. LA had a very laid back feel to it. Maybe it has to do with all the space. NYC is pure congestion. Wherever you are, a few hundred people around you are trying to pass through that same space. It keeps you moving, hustling to keep from being run over or an obstacle. I loved both cities, but they have very different "feels".
I'm not sure it's truly accurate, but the east coast, DC and NYC in particular, feel like a dog-eat-dog, I'll do anything to get ahead, kind of place while the bay area feels like a much more friendly competitive environment.
Whatever the cause, there is a very real difference in attitude between the two coasts.