The point about facing the wall is interesting. I find it very difficult to concentrate if I'm not facing _away_ from a wall. Knowing that people can come up behind me as I'm working or taking a break makes me very uncomfortable, to the point that I can't really relax and get into the flow of my work. It just feels like I'm being constantly watched.

Of course, cubes or offices would let us have the best of both worlds, but ...