I am right there with you b/c my dd5 just falls asleep early. In fact, for the past two years she has fallen asleep at Disney at 7:30 p.m. EVERY NIGHT no matter where we were

One night she was asleep during Spectro and Wishes, one night she literally fell asleep IN the pool (on my dh's shoulder).
But my other ds would be up later so it is tricky in one room. Usually dh would take him down to the arcade at the hotel and let him play while dd slept and come back when he was ready to sleep. Of course he was the tough one to wake in the morning, but it worked.
Another suggestion I have, which I got off of the organizational tips board, was to bring a cheap plastic shower curtain and put it between the beds so you could split the room up. I plan to use this for the baby but not sure if it work work for your dd.
Most nights, however, we were just as tired as the kids and fell asleep right with them!