I've mostly been active around Palo Alto and Mountain View, which is ultimately my biggest mistake. The long and the short of it is, people from the larger companies generally don't seem interested in "extracurricular" activity, and students at local colleges don't stick around in the area. The most enthusiastic hackers here are growth hackers, which I am not and don't care for. I also get a lot of individuals who feel like they're washing out of their profession, but that's not the same mindset as tech enthusiasm.
I agree that fishing in San Jose proper is likely to turn out more students, recent grads, and other kinds of people who are more about exploring and trying things.