So, starting with the basic concept of "carousel with screens", imagine what they could do if they plopped a carousel down in the middle of the finale room of Mystic Manor. You enter through the house, Mary has somehow stretched the nursery larger and put a carousel in the middle. It starts to rotate and the walls are suddenly magic. Some perhaps break away to show additional screens or a scene behind it.
Or less probable, to steal an idea from Universal, go the full Poseidon's Fury route and the nursery isnt screens but actual walls and the entire nursery disappears to reveal the screens beyond.
Something along those lines could open some interesting possibilities.
I did like the idea someone posted a few pages back of individual "horses" that operate like Luigi's in DCA. (Though they'd probably have to be some kind of car/bench rather than actual carousel horses) You *think* it's a carousel, but then the horses start to dance around the room.
-Rob