While we're bein' smart-asses
I would suggest Footloose. Be sure to include a couple of the classic Kevin Bacon moves from the movie. This is a great one to go out into the audience to. Find a hot girl, pull her up from her seat and show her what you're made of...
OK, SORRY - I just couldn't resist...
Seriously, a good tune should be:
-One that most of the audience will recognize and like.
-One that has a beat that you can pose, too. Something with a strong rhythm that lets you hit poses authority and hold them long enough to show your physique in that pose.
-The above also helps if you mess up your routine - just continue the poses on the beat until you time is up and no one will know the difference.
-Pick a song that you really dig, cuz you'll be listening to it a shitload. Good songs for training are not necessarily good songs for posing. Speed metal is probably not a good choice.
Hope that helps.
-Randy