No, children do not belong in premium cabins. As a previous poster mentioned their behavior is just too unpredictable. Parents shouldn't be so selfish and think of others. I and others pay a lot of money to sit in premium cabins and expect a quiet and relaxing atmosphere. One of the worst flights I remember was an MEM-ATL segment where two kids were sitting with their parents in first class. They were classic examples of absentee parents. One of the kids wouldn't stop crying and both of them kept climbing over the seats and kept switching seats next to the parents. I'd say around age 12 children are able to control their emotions and behave well enough to sit in premium cabins.