I grew up in La Jolla, and have lived in Boulder, LA and NYC. For me the Bay Area just works, especially Berkeley where I live. The town is very bike friendly, 15 minutes from downtown SF, and all the stuff you would expect in a major urban college town.

But what really works for me is how easily you transition from urban to..."out". The hills are 25 miles of interconnected open space and parks. i can ride up to about 80 miles with 2 or 3 stop lights and a couple of stop signs. Whether you are east bay, peninsula or Marin there is just a ton of open space for cyclists, easily accessible. You do climb a lot though :-).