Be sure and get a good DJ (pick me, pick me lol) also.
I have found with every wedding dance I have done the couple do not take into account the dance as it co-incides with the photographer. Try to keep your wedding/dinner/dance as close to schedule as you can. I have rarely ever started the dance on time. I try to co-ordinate the dances that need photographed (first dance, mother-son, garter belt toss, etc.....) as the very first ones so the photographer does not stay longer than is needed. If the dance is to start at 8, you don't want to still be serving food at 7:50.