We often joke about the "Man Cave", but we (meaning men) like to have one. Why? Because usually the rest of the house in controlled by the woman. The German mirrored beer shields and cavalry sword are NOT being displayed in most living rooms. Thus, the need for a man cave.
I'll be getting the better part of a room as my office / workout / man cave. Which is cool. I'll have a place to display my beer memorabilia, a small selection of my games, my miniatures, my signed art prints and other assorted stuff. The rest of the house will have dolphins, seashells and an assortment of nicknacks. The lady gets to decorate everything but my man corner, and that's OK.
I'm just glad I secured my little corner ;)