After my employer was acquired we adopted the new owners' "unlimited" vacation policy. I have heard from a manager in another part of the business that her staff now take less holiday, but for my team I'm making it clear that I wish them to take at least 20 days off per year. That's 5 days more than we were officially allowed previously. I figure that if they go around claiming vacation is unlimited they don't have much choice if someone holds them to it (and 20 days really isn't that much).