I think this could be a thread of its own, since I haven't seen it discussed here before. So, what's your take on dancing and DJing?* Don't dance and DJ ... a song here and there is fine, but you can't really do both.
Personally, I almost never do it; I find that it screws up the dancing and the DJing both. Perhaps a song or two late at night when there are few people left and the mood is a bit more relaxed. Even then, I prefer to put on a compilation or a CD with a couple of tracks that can be played in a row, so I don't have to run back to press Play at the end of the song.
Of course, I DJ from CDs; if you have a laptop with a playlist made up in advance it's much easier. I still don't think I would like do it a lot, though. I do want to watch the floor.
That's just me, though. Some people do it all the time and it seems to work for them. Is it just a question of your ability to multitask? Or is this a bad habit that should be discouraged?