I'd also have to say as a D.J. that brides that try to make the D.J. the hired their own personal jukebox by giving him a huge list of songs to play as well as a list of do not play songs are on tract to ruin their own reception. While the wedding is all about the bride and groom, the dancing party at the reception should be all about making your guests happy after all the $$ they forked over to attend your reception. 4 hours of the favorite songs of a 20 year old will not be getting grandma and grandpa up on the dance floor. You hopefully have hired a D.J. with many years of experience and a good D.J. will play music from all eras and in all styles during the evening to please all your guests.