We are sailing on The Summit from Los Angeles to Hawaii during Christmas and New Year this year.
I have sailed before on Carnival and Royal Caribbean during the holidays.
From what I've read about Celebrity's dress attire in the dining room, and the mere cost of the cruise, I believe that any childeren that are on board will be very well behaved. I'm not worried in the least.
Although, I can honestly say, that I have never really encountered any real problems with any of the kids on board of any of the cruises I have been on.