The main thing, next to privacy, that tweens need is space: a space to hang out with their friends, a dance space to work out all of that preteen anxiety and, of course, plenty of space to accommodate sleepovers. And then there are the clothes. As your tweens become teens, you'll want to make sure their ever-expanding wardrobes aren't spread all over the floor, so make sure there's plenty of space to stay organized.
Invest in space-saving organizers for closets, and check out under-bed storage to create more floor space. When it comes to seeing your teen's floor, just keep your fingers crossed.