A small space idea, like a tree house in your room. Utilize all space with shelf stairs up to the bed box. Get a closet too and all of it up off the floor space. Great for a boys room. Put a BB Net on the bed and voila! they can play indoors.
Lofted beds with walk-in closet underneath. Good when you're short on bedrooms for all of the kids. Loft beds and instead of a closet underneath, it could be the kids "rooms" for private and quiet time.