Large room challenges

I am reasonably familiar with the acoustic challenges in the small to moderate room.

What are the different challenges in a large room, say like hotel ballroom setup during shows?
Time to talk to a Pro Audio guy who does this work on a routine basis, all others would be just guessing.
Yes, speaking with a professional is the correct path. I have noticed these rooms do have a bass traps on the walls. A ballroom size space is going to have issues with being to lively and would need to be deadened somewhat for music.
The rooms sound will change drastically once it is full of people.