They have a kids show for all the kids in the lab towards the end of the cruise. It's a cute little thing with Mickey Mouse, and they all get free shirts. Be sure they participate in that, and that you are in the audience with your camera...you'll cry!
I agree on "making" your kids go to most of the main shows every night, they almost assuredly won't be disappointed.
The free ice cream at Scoops is a big hit. I think the boarding buffet is the poorest meal from a kids point of view, so we now skip it and eat burgers and chicken nuggets at Plutos as soon as it opens by the pool.
If you trust them, let the older kids check themselves in/out of the lab; that makes a big impression.
You've got some younger kids so I'd try to get the early seating so they don't end up face down in their dinner asleep. I find they can make it through dinner, see a show, then crash.
Don't even think about missing Disney Dreams. Or the chocolate souffle at Palo.
Consider having a surprise package waiting in your cabin for the kids. Shirley at The Perfect Gift can hook you up.
Get up and off the boat early and make a full day of
Castaway Cay, you won't regret it.
If you and the kids drink a lot of soda, bring a case on board and buy more at each port. Or decide if you want to invest in unlimited soda mugs.
If the kids already own snorkel gear, you can save a bunch if you bring it, but you have to weigh the hassle of bringing it. We have prescription masks so it was a no-brainer.
I'm going on a 4-day in November, but want to go on another 7 day...can I go in your luggage?