Almost all ballrooms have some sort of rigging points in my area. Some are only moderately useful. 12' to the bottom of a
truss is about the lowest I want to hang anything. So overall height to the ceiling needs to be about 15' or higher.
I run into a lot of places that have perfectly good 1000 lbs +
point, that are only rated for an almost useless 500 lbs, simply because the hotel asked an engineer "can we hang 500 lbs on this?" Rather than "what is the maximum weight we can hang on this."
But as far as Usefulness goes, except for where a couple speakers on sticks will
cover it, almost any time you can fly PA its going to sound better than
ground stacked. Lighting can become a moot
point in a small room, if I can get a similar angle from a pair of 15' towers with a couple lekos on each, as a flown
truss that can only get to 12' off the
ground, yeah it still looks like crap, but a lot of times its not worth the extra work and cost of riggers at that
point.