We just returned from the Hurrican Frances Navigator cruise and we were amazed how many parents had their very young children (one particular couple were bringing their infant no older than 4-6 months and 2 year old) everywhere at all hours. We saw them numerous times at midnight, 1 AM all over the ship with these poor kids. My wife categorized it as "child abuse".
Twice we were hoping to enjoy the quiet jazz in the Cosmopolitan Lounge overlooking the pool area at midnight or later and there were young toddlers there whose parents were not as tuned in to those around them. The kids were obviously overtired, whining, and the parents were oblivious to it. The daily compass specifically stated that this venue was reserved for adults over 18 after 10:00 PM at night. It definately detracts from your own quiet enjoyement when this occurs.
While the crew did an admirable job during the day keeping the young ones from the adult solarium pool, they did less than stellar job in the lounges and the theater. Two of the striclty adult shows, which were publicized as adult shows, there were many kids in attendance, and when a performer used some adult language, one actually apologized because kids were in the front row.
There is a time an place for us all, and as a parent of two children, I love them dearly, as we all do, however, parents need to use common sense. A six month old or two year old has no place in an adult club after midnight, no matter how good they may be.
My humble opinion.