We moved into a shared office space in London which an early investor helped to hook us up with. It sucked. It was a crummy, distracting environment. A lot of people there were working on pretty weird/lame projects (including a Russian "get rich quick!" motivational speaker, who was apparently had eight-digit wealth but worked from a £100p/m office space).
Things which are poisonous to your productivity:
• "Networking" events of any kind • Talkative people who are working on projects which they don't believe in • Talkative people who are working on projects which they do believe in • People from other projects who want your advice on something • People from other projects who have heard you just did a raise and want to ask questions • People from other projects who want you to test something really quickly just this once • "Oh you must just meet this person they're so relevant to your project" • Anyone talking on the phone for any length of time (this is personal. I find it annoying to hear one-sided conversations).
We just moved in to shared office space with a YC company and another company. It has only been a week or so but already we're more productive and it feels more like "work" (in a good way). Fewer meeting rooms but fewer distractions. More focus.
Don't go to a shared workspace. You'll do poor quality work with a ton of distractions. Find another company who have some spare desks, and go there.
Working from home is not productive for most people (hence all the "HOW TO BE PRODUCTIVE WORKING FROM HOME" linkbait articles you see all over Lifehacker and occasionally on HN).
It's also a psychological help to have somewhere that you invite people: you invite investors to your office, you don't go to them. Even being able to say "we can do it at our place?" makes you seem like you have clout.
HTH.