WeWork is actually perfect for startups; they sell no commitment pay by the month office space that comes with desks and internet. They're cheaper than most sf office space and an order of magnitude easier to rent.

The sole drawback is they're an unmaintained dump and working in one is an utterly miserable experience. I had the very very unfortunate experience of working at 995 Market and these worthless idiots couldn't even get their elevators to regularly work, and just plain didn't give a damn. Who doesn't enjoy a nice 15 minute break while you wait for an elevator (both ways)? The offices are tiny and LOUD. Some other idiot decided to make the floors hardwood; a single person in heels walking down the long shared corridors goes CLACK CLACK CLACK. The walls are transparent glass so you are distracted by every bit of movement. There's no sound insulation so you get to listen to the office 3 doors down discuss their thanksgiving plans. I really can't say enough bad things about it.

But hey, there's lemon water in the kitchen! (In a leaky carafe that makes a puddle on the counter every day. Naturally.)