I want to live someplace I can get around by bicycle. Perhaps that's technically possible in, say, mountain view, but mountain view isn't really a town unto itself, but a suburb or exurb or something. For all practical purposes, all those peninsula towns are part of a big, urban area that stretches from SF to San Jose. I agree that it would be good in a lot of other ways, and it's a tough decision, but in terms of livability I get sick of it every time I'm there, and I'm unenthusiastic about trying to raise a child there.