Just by joining I've met some really great people and that has created many opportunities and generated more business for my company.
I would guess SF would be more expensive but I only pay $100. In the big scheme of things, it's worth the money and I use the office 2-3 days a week.
but also, there is quite some overhead attached to it, especially when compared to working from home.
a) the commute. that is time essentially totally unproductive and costs you either BART tickets or gasoline.
b) the distraction: while it's fun being around other people, I've seen how much people talk to each other, in terms of productivity it is not that great. there are a lot of people coming in from everywhere, and everyone is interesting to talk to. but that's exactly the problem. while you're talking to them you're not moving your product ahead. of course you need to have a healthy balance of networking also, since you can generate sales/hire/partner leads with it. but for that, a cowork space is just not focused enough
c) equipment/food etc. if you work from home, you need everything just once, you have 24h access to your fridge, you don't have to carry laptops around or screens etc. and you will save money since you don't have to go out for lunch and can just cook or eat frozen food at home.
I am lucky since a have a cofounder, I guess that makes it easier to stay and work from home.
Then again, I would seriously think about getting a cofounder, I feel it's much more productive and fun.
I've discovered that I'm next to worthless when I work from home, so I'm looking forward to setting up shop there.
If I feel antsy I hop on my bike and head over the bridge. =)