I think you will find that the kids will go to the activities if there is something they really want to do. They can eat ANYTIME on a cruise, so they won't go hungry. The good thing is that the Camp Carnival activities are listed in the Caper Paper everyday so you will be able to discuss them and determine if you need to worry about the kiddos for dinner. You will probably end up having them with you on at least half the nights.
Its a good excuse to try the Supper Club if your ship has one.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007