When I first moved to SF in 2008, I choose to use both coffee shops & co-working spaces as a way to meet likeminded people. My approach was.

1) Every co-working space will usually give you 1 free day to try it out, or offer a low cost "open" membership (ex: 5 days a month). So you can always do that, and try them out.

2) Find a list of the top coffee shops in SF for entrepreneurs, and spend time there. I use to go to 1-2 places in the morning, then the afternoon. So 9-10:30 at one spot, then move to the next. If you go the same time every day, you might get to meet people who do the same and that's a great way to build a relationship.

The things I did that work were
- Asked the owners of the place if there was anyone they'd recommend you meet, that shared similar passions or projects, or had recently moved to the city.
- Ask people if they have lunch plans, and want to join you. Best to do this once you've made at least one friend, but works either way.
- Participate in events or other organized things (like lunch events, or talks at co-working spaces).

If you do this, you'll find the place you like the best ... don't settle too quick, spend some time getting to know the city and the people. It's such a wonderful place.