Recommend trying to find something short term in SF. Apart from the fact that all the major startups (Twitter, Obvious Corp, Pinterest, Airbnb, Square, etc) are based in SF, it's only a 35-40 min drive to Mountain View and most importantly, you'll be able to connect more easily with YC alum mostly living in SF. Check Craigslist SF Bay for short term, furnished housing.
Even Zuck prefers to live in SF (he has a house in Palo Alto 'only' because of office proximity). Ron Conway lives in SF. Marissa Mayer (except when she has to be at Yahoo), Drew Houston, Jack Dorsey, David Sacks, etc - all live in SF. Everyone commutes via shuttle/train to Mountain View or Menlo/PA.
