We only pack one pair of long pants & have them take it off right after dinner to save for wear again on semiformal night.
We pack nice docker style shorts for the other nights, but pack only about
2 - 3 of them since they can usually reuse them as well. Don't forget you can wear your pirate attire one night to dinner which makes it more casual. And you kids may not dine in the main dining room one night, if you're going to Palo and choose to feed them at Topsiders, by the pool, or my boys' favorite room service while we get gussied up. There is also usually one night when the boys have just had too much fun/sun or are too wound up to sit through a formal meal and we let them eat w/ the kids club. They enjoy doing this once on the trip b/c of an event that is immediately following it that they want to be part of. Check the navigators to pre-plan some of this.
We pack nice polos or short sleeve dressier shirts. (Having boys I can honestly say we could almost never reuse those--somebody always gets somethng on the them or more likely wipes something on them
)
My boys were 4 & 7 on our 1st cruise and 6 & 9 on our 2nd.
We do not bring dress shoes at all. We have one pair of nice sandals that they can use. In the formal pictures, you don't see the kids feets. In some of the photos, they post the whole family w/o shoes on a white backdrop.
Yes, there is debate on this but we have noticed that many people allow their kids to wear nice shorts w/ a nice polo/shirt. I also think that the younger the child is, the more likely it is for that child to be dressed down more. No one will EVER say anything to you about your children's attire. Do what's most comfortable for your family.
Towels--your rooms steward can bring you extra towels the night before an excursion. On CC they have them there for you--I think.