Remember: no matter how nice it is, a ballroom is nothing without music. At the very least, you'll need to hire the services of a disc jockey, or ideally a complete band. The type of music depends on the type of dancing, of course, but it's a good idea to get a band or DJ with some flexibility in their style.
Some ballrooms may throw in a house band with any rental. This is a good way to save money on the music, but you'll have to be certain the music is appropriate. In most cases, you'll get something like a swing band, a blues/jazz band, or even something a bit more eclectic.