A large portion of jobs in the bay area are in Silicon Valley which is south of SF and comprised of cities like San Jose, Palo Alto, and Sunnyvale. For someone seeking the amenities of a global city like SF, none of the other cities in the bay area come remotely close. They're all generally quiet, clean, suburban locales except San Jose which is a sprawling mid-sized city but still nothing like SF for someone wanting a world class city.

You know how you can tell a city is world class? When you don't have to tell people it's a world class city.