I use to wish we had a room like barbie and the 12 dancing princess's. It would definately work for us.
Our sleeping arrangements are DD1 (13) in her own room. She definately needs her own space.
Then in our room we have our king bed that accommodates DH, DD3 and I and also a single bed at the foot of our bed which has DD2 in it most nights. Occassionally DD2 will sleep in her own room or with DD1 (who likes her in there sometimes)