I agree with PDN's approach. I would add to the suggestion that you consider using omnidirectional speakers since they will give you a wider sound field and may work well in your situation. Experiment with placement. There are some good deals on omnidirectional speakers on Audiogon pretty regularly so keep an eye out. Another interesting option would be to mount soundsphere speakers (or something similar) overhead and not worry about bumping into speakers or tripping over wires. Just a couple more ideas to think about.
Challenging Speaker Situation
I have a 20' x 20' billiard room. Other than the usual square room concerns, I am looking for the best type of speakers (and their placement) to use when I'm standing and shooting a few racks. I want to get quality sound up at the listening height, but still need the music to fill this relatively large room. I like a well balanced sound quality, and will be listening to mainly jazz and rock. Amplification isn't a concern, as I have a variety from which to choose, one of which would match just about any speaker that I use. Any advice would be appreciated.