Good coffee shops are certainly adequate, and many of them, in Europe anyway, have a section that is nicely furnished for a full day's work.

There are some extra perks to a good co-working space, though. It is library-quiet, and you are surrounded by people who are living and working a similar plan. I was actually able to informally recruit a guy who often worked near me, when we needed to bang out a bunch of UI components and their services, for a design that the client and I had already detailed fairly well.