Should I go to San Francisco by myself?

$600 is more than enough to live in SF for a couple of weeks provided you have a place to stay and travel expenses taken care of. I did this for 6 weeks, had a place to stay, and had my travel taken care of. I had about $450 which covered food, drinks, and a few souvenirs. It helps if you're a young attractive male, you can probably find someone to pay for you on some things, especially drinks - just be careful!