Zappos would drive me crazy. I have been in an environment like that. It's "cute" at first, but then you realize you're just living in a messy corporate cubicle. It really inhibits work if your job is something such as development or design, in my opinion... just too much visual noise.

37signals office seems virtually distraction-free. If you need groups of people to work together efficiently in an office environment (that is still comfortable and not a cubicle farm), this is the kind of space works well, I think. Because they have so many remote employees, I think they want their real "office" to be Campfire anyway.

There is a significant difference in philosophy with how the companies operate, I think. Zappos wants people to be comfortable (or 'at home') where they work, and 37signals wants people to work wherever they are comfortable.