I thought I would post a few thoughts regarding the advantages and the disadvantages of brides and groom creating their own play lists for the DJ. I'm thinking about this because I did a Soundsations (my mobile DJ company) wedding dance in Edmonton a few weeks ago where the couple had provided me with a list of about 20 songs that they definitely had to have played and about 10 songs or so that they didn't want.
Normally when I meet with a couple at booking time I tell them that, of course you are welcome to put together a list of must play and do not play music. After all, It's your big day and you're the customer. I usually also say though, I can only play so many songs during a four hour or so dance, so if your list of must plays is huge, I have no flexibility to play other guests requests. Also, if what you have listed isn't working, I don't have as much flexibility to try and read the crowd and play to them. It could be that you don't care if the dance floor is busy, as long as you're hearing the music you like, but that isn't usually the case.
I also warn couples that chances are someone will request the very songs you've asked not to hear. These may also very well be the exact songs that would get the dance floor busy, even though you might cringe when you hear it.
An experienced DJ that has performed hundreds of dances knows what the average mixed aged crowd will respond to. They will also be able to adjust what they are playing based on requests and a little trial and error. Dictating a huge must play list to the DJ severely handicaps the DJ's ability to do this. It is also quite awkward for the DJ to have to tell guests "I'm sorry, the bride and groom don't want to hear that song.".
In the end of course, the customer is always right. but if close to a 500 weddings worth of experience is worth anything, my advice would be that if you have music you definitely have to hear at your dance, give the DJ a list of no more than 10 songs or so. Also keep your do not play list to a couple of songs at most, or even better, tell the DJ only to play them if requested.