There's a term for kids who are hurtling toward adolescence, but it's preteen no more. They're called tweens, and they have their own important role in the marketplace, driven by a slew of retailers making products that appeal especially to them.
Given that tweens are still family-bound and too young to be out with their friends all the time, they spend a lot of time in their rooms. Playful color palettes and creativity reign supreme, but a hangout spot is essential to accommodate their growing group of friends.
It's a transitional age, so you should be designing a transitional bedroom. Think of it as buying a pair of pants that's a bit too long so that you can slowly let the hem out.