I have to disagree about not registering your kids. Yes, you don't HAVE to do it, but there are a couple of good reasons to go ahead.
1) A lot of kids will make friends that first evening, and it's hard to come into an established group. Particularly true with the club kids according to what I've read here.
2) If you get separated from your child, if you aren't registered, it's MUCH harder for them to contact you. This happened to us on our first trip. DH took the kids to the pool while I unpacked. DD came back to our cabin (except she mixed up 7005 to be 7050 and went to the wrong room). This all happened right at the life boat drill, and no one could help us since all services were shut down. We didn't get her back for almost an hour! They had to look her up in the reservation computer and bring her to us. If she had been registered, they could have paged us saying where she was, and it would have been resolved much more quickly. Needless to say, 2nd cruise, we were among the first people at the lab to register the kids. It's actually not busy at all in the timeframe before the boat drill. There were probably 5-8 families registering, and about 8 CMs available to take care of you. The busy time is when they first open just after the boat drill (I think it's about 5 pm).
I don't mean to scare anyone. My DD was perfectly safe, but I don't want anyone to go through what I did when there's a very easy solution.
Enjoy your cruise!!