Posing - frankly, you have Round 1+2 to pose in all serious, with no music, straight to the point. In Round 3, in the evening, you should have fun, pose to whatever music you want, and make it somewhat entertaining to the audience.
It is all what you make it. Jay Cutler poses to slower music, but he does it in a dramatic way, so it makes it interesting to watch. I would rather watch Melvin Anthony, Kai Greene, Darrem Charles, and others who make it entertaining as well as show of their physique than another bodybuilder who just gets on stage with really slow music.