I like long vacations and by long I mean those lasting 3 or more weeks. This makes me employable only in Europe which is fine.
Two weeks or less do not seem to be enough to rest my mind and certainly are not enough to get to know the country we happen to be visiting. We almost always visit just one at a time and while a month is not enough either, at least you get a sense of scope and size of your ignorance.
It occurred to me today that benefits to my employer(s) go beyond me being more productive and creative when properly rested. Most organisations, even dysfunctional ones, can muddle through a two week absence of almost everyone. Some tasks might be delayed a bit or done slightly worse than usually, but few things are generally really time sensitive or can't tolerate a short dip in quality.
Longer absences however expose faults and cracks and test the real bus factor of a missing person. They will expose which bits can or are picked up by others and which suffer. Also how much strain team can bear or would need to if that person suddenly left.
You can't really buy this kind of learning other then by encouraging your employees to take long vacations.