DJs are people who read the crowd, decide on the song and play it.
Bingo! I do a lot of mobile DJing, and I can tell you, that's the hardest part about it. And we take it personally when people do not dance, unless the bride or groom requests a song that bombs
. But seriously, a good DJ will keep the floor packed, because we know songs that get people moving, and songs similar to whatever gets people on the floor. We have those "ace up the sleeve" songs in case it train wrecks, etc. And iTunes can't beat match, mash songs, and pump up a crowd. iTunes doesn't understand that you need to keep the tempo of the dance floor as high as possible and if you can keep the tempo similar to the previous song, more people will remain on the floor.
Also, how you organize the music can make...and break...a reception. If you try to do it in sets, like say pop music from the 90's, rock from the 80's...whatever the genre's are...and group them together. It could work. But if people don't dance to the first song in that genre, than what? Now you've got an empty floor for several songs. What about slow songs, how do you decide when to do that? Is everyone tired of dancing to fast music after 3 songs, or 7? What about the formal events, like tossing the bouquet, the first dances, the toasts, etc?
The difference between a DJ and using iTunes is the difference in how many people stick around after the first few minutes.
Now I'm biased, since I DJ these kinds of events, but I can tell you when I get married, choosing the right DJ is going to be the task I'm charged with, because I understand how important it is. I would never dream of using automatic software like that.
But that's my experience and opinion. I do wish you luck in your wedding, though!
