Conversely open-plan is my least favourite. It appears to be a system designed to maximize interrupts, distractions and context switches, and to minimize productivity, morale and concentration. As far as I'm concerned, "open plan" is the Evil incarnate.
I would never willingly subject a group of knowledge workers to that environment. When we grow Fogbeam to the point that we have employees and actual office space, my intention is to ensure that everybody has a private office, with a door that closes. Or, at least, that everybody is offered such a thing. If some people want to work in a different configuration, I wouldn't want to force them into an office when they don't want it.
My dream configuration has always been "a private office for every individual" and then complemented by several large open area with plenty of couches, chairs, tables, and whiteboards on wheels (and good wi-fi, of course) so that teams, small groups, and individuals can create ad-hoc, temporary configurations that suit them when they need to be co-located, but yet everybody has an office of their own they can retreat to when they need intense focus and privacy.