This model was taken from the Brawl trophy of Luigi's Mansion that the Project M Development Team could use.
It's essentially a recreation of Peach's castle to my best attempt, except for one obvious change: The roof thingies. I was thinking something akin to what Mmmmmmmmmmm said: (who has a cool profile picture too) Spontaneous platforms! I think that, similarly to the ghost in Yoshi's Island, at certain intervals of time, two platforms would rise off of the roof, with a similar visual to the entire Mansion rising from the ground, and, instead of a Fly Guy demonstrating that the platforms would rise, it would be an orange ghost doing its' whole ghosty deal.
Now that I think of it, they could possibly implement other spontaneous platforms with a visual of the pink Boos in Super Mario Sunshine, though I personally like the simplicity of just two platforms.
I think it would be more fun if the center spire was taller and if the stage was bigger in general.
All I know are visuals. Sorry.