Great to chat with you as well, great conversation and I appreciate the hard questions. Median teacher salary in 2012 was $59k according to public school data, restaurant servers with tips make the highest salary per geo of the restaurant industry in San Francisco clocking in at $50k base with between $20-50k in tips totaling $70k to $100k. We don't want to stop at $50k as a baseline though. Our 3 buildings under construction will have suites that can be afforded on a $25k a year salary. Our goal is to build, at scale, for those making minimum wage. We can only do that by brining down the cost of housing further which is the core focus of our business.
In San Francisco the pendulum has definitely swung back closer to center (the scale being all open to combination of open and private to private office intensive) with most startups occupying a hybrid solution with a myriad of breakout rooms and smaller meeting spaces / soft seating.
The trend over the last decade began with die-hard open office plan fanpeople (breaking free of dads private office intensive historical), who quickly found that there was a lot of counterproductive distractions. From there as more traditional business starting adopting a start-up mentality to their office space, a balance had to be struck to ensure productivity.
Now the offices of Airbnb, Optimizely, Weebly, all have very strong distribution of open communal work area with solid guidelines from a cultural perspective on how to treat people in that environment, while also matching the open area with ample meeting space distributed evenly throughout their building.
With a more thoughtful approach than just open vs not open I think a balance can be readily created while also speaking to the culture of the company and genre of business it functions in (gaming, Saas, mobile, etc.).
For the record
1- 10 years
2- open (3.5 yrs) vs closed (6.5 yrs)
3- dozens but you learn the headphone rule which basically means (don't bother me or text / message me)
I don't see meeting rooms as a balance. It doesn't solve the increased distraction of an open floorpan. Also, meeting rooms that are communal are not as useful- consider a whiteboard on a communal meeting room vs. one in a small office that houses 2-3 developers. That office whiteboard can have project info on it for weeks, while the communal one can't be left there.
For me, in an open office, having headphones on is not enough. There's visual distraction as well. People interacting in your field of vision are also a distraction.
I work in a place that has open offices, but broken into pods of 20 or so desks. In addition to that there are meeting rooms and a more general-use area. It's rather similar to the start up offices you describe (I have seen Airbnb's in person).
I like this setup, I find it freeing because you can move to where you are more comfortable working at any given time. But the catch is, you can't just say seating is "variable" as a way of punting on giving people desks. Everyone should have a place that undisputedly belongs to them.