It is really a personal choice and you have to look at your own family and habits. You don't miss anything since each show is shown twice opposite each sitting, plus the all time favorite, Disney Dreams even has a matinee.
Don't forget about time zones, if you are a West Coast person, your body time clock will think the 6 pm dinner is really 3 pm, at least for the first couple days. We did the early dinner our first cruise and changed to late on our second, it just works better for us.
How do you other parents get your children to sleep early of the cruise???? Our kids outlasted us every night, though I must admit the kids didn't have breakfast most mornings and we did. Of course our kids are older but even our 10 year old lasted til midnight every night.
Leslie