If you get exhausted by working a lot, it's probably best to not work at a small startup or a company that is growing super fast. There are larger (usually public) companies in the Bay Area where people can work 9-6 type jobs and be great at their jobs. It can be team dependent, but there are people who work totally normal hours at google, apple, linkedin, etc. There are a lot of other mature companies people work at as well. It's not as sexy to say you work for them, but they pay you a respectable salary and don't have to take over your life. That said, ANY job can take over your life if you let it, whether that job is in Portland, Austin, Chicago, or San Francisco (not that it is necessarily a bad thing to have your job be your life).