I don't know what your experience is with "open offices", but the ones I have worked in where quite loud and distracting. That isn't to say that I discount the images of people sitting elbow to elbow in coffee shops.
Coffee shops are, in my experience, quite a bit quieter then open offices and less distracting too.
I would honestly prefer going to a coffee shop to work then a "open office", but also I am really thankful that I don't have to do either.