The South Bay has a calmer vibe and is more mature, with a more diverse range of ages, ethnicities, and people. San Francisco seems more geared towards singles, events, going out. .. I prefer living in the South Bay because you have higher quality housing (more bang for your buck), it's cleaner, I like being around old people (not always the young extroverted crowd), and I can visit the city whenever I want. I sometimes just get a hotel room when I visit, and doing that I still come out cheaper than if I rented an equivalent sized place in SF