Assume you mean private office. Isn't that a pretty compelling argument that the majority don't see big advantages to open plan?
That's a one time cost. Amortize that out over a 5 year office lease and it is peanuts compared to the productivity gains and lower turnover.
Also once you go with a private or semi private office you won't want to go back. Any employee from there interviewing at places with open offices will probably think how much they will hate it there.
I know the occasional person will pop up with the "I love hearing other people jibber jabber throughout the day!" But 9 out of 10 people I talk with would rather not.
Quiet rooms don't help, not everyone has a laptop, nor wants one. You end up with a crappy, un-ergonomic desktop environments. And there are only so many quiet rooms possible. If you use one continually, you get marked as the social deviant.
Shareable offices? How is that any different than the old "hoteling" concept? Sharing an office is going to be first come first served, same as your quiet rooms. No diff.
If managers, directors, and VPs are willing to use this type of setup, I'd be more tolerant. But in our latest update, they all have dedicated offices. They can't mingle with the hoi polloi, having an office is a signal of their power and prestige.
The best permutation of open spaces and privacy that I've seen is a wide open space with quiet rooms and sharable offices. Work in the open space when you want, or work in the quiet room when you need some privacy.
I wish that more companies would adopt this.