By far the most collaborative environments for me have been individual offices or two to an office.
In an open floorplan I find myself constantly being distracted and trying to wall people off, which makes my emotional state less open to discussion... because I'm trying to focus on work.
With an office with one or two people in it, you don't have to worry as much, can be more open because you know you will get time to focus.
The company I work for is moving from individual offices to an open floor plan. They didn't even bother to talk to programmers about it, and admitted they looked at individual office locations but didn't think it mattered when we protested.
They've also gone from a 6 person dev team to now 3. While there are many problems that caused me and the other two people to leave, them choosing an open office without consulting use and then blowing off our objections is characteristic of the disrespect they show generally.
I think that companies with open office plans don't really respect engineers. And I include google and Facebook in this assessment.
http://i.dailymail.co.uk/i/pix/2013/05/27/article-2331658-1A...
http://www.dailymail.co.uk/sciencetech/article-2584738/Now-T...