- There are certainly high rises in downtown SF that comfortably fit 8000+ people. - Tech company employees live in the south bay mostly because that's where t

- There are certainly high rises in downtown SF that comfortably fit 8000+ people. - Tech company employees live in the south bay mostly because that's where the tech companies are, not the other way around. - Reaching SF from the east bay is much easier than reaching Mountain View/Palo Alto from the east bay; in general SF seems like a better compromise for commute access from the whole region. - Not requiring parking was kind of the OP's point. Put the office somewhere with actually decent transit access, and build no parking at all. - Skyscrapers work fine for big finance companies even more paranoid about their secrets than Apple and Facebook. - Plenty of companies larger, smaller or of comparable size to Facebook find that a skyscraper in a real city makes sense. I think the real answer to the OP's question is mainly that the extreme power of NIMBYs in California makes it nearly impossible to build new tall buildings, so truly urban office space is in very short supply. Indeed, it can be difficult to build much of anything in California that isn't more or less in the middle of nowhere -- Facebook and Google are both practically in the Bay! The development of SoMa may prove something of an exception to this, and it will be interesting to see if many tech companies move into the new office space planned there.