I really want this also. I'd love all sorts of ballroom dances added in from waltzes, foxtrots, tangos, salsas, rumbas, jive you name it.
I'd like it for making glittering parties or for vampire gatherings. We could have our own dancing with the stars even. I hope at the very least we get a few different couple dances when they come. Since that would be very animated I'm not sure we could get that many couples dances but I'd like to see them have a learning curve like the first dance would be awkward. The second maybe that sway slow dance that is pretty common and then up from there.
I also hope they throw in a few face to face club dances too.. but that doesn't hold a candle to a ballroom experience.