I can provide a bit of input for what we would do differently
First - we packed beach towels - not so much for the pools on board but for Castaway Cay - and it was overkill. They took up too much room and we could have used the towels handed out by the CMs just fine.
Second - we took beer and wine on in our carry on - but didn't even drink it as we were trying different drinks and stuff on board. While it might be nice to bring on a bottle of wine for the verandah - it was a waste of space since we purchased it onboard anyway.
Instead of using the space for beer/wine - we would pack canned/boxed drinks. They are pricey from room service and sometimes (like midnight) we were just too lazy to go to deck 11 to fill our cups or they would get too watered down hanging around the room.
We would spend more time exploring the boat. There was so much I feel like we missed out on (mid-ship detective agency - general pictures of the detail - etc).
I would try to plan time better - We only made it to one show and didn't even catch a movie on board. I know it's impossible to do it all - but I still can't figure out how the four nights passed by us so quickly.
I would not be out as late on pirate night so that I could do the Castaway Cay 5K - I was really disappointed that I didn't plan for that better.
We would leave our bags out the night before disembarkation. This time we did the express walk off and it was such a hassle trying to maneuver a stroller and our luggage down the halls - with the cleaning carts out - to get off the boat - and when we got into the terminal a lot of luggage was already there and porters were waiting to assist. In the future - we will place our bags out the night before, still do the express walk off - and hopefully our bags will beat us to the port.
That's all I have for now - but if anything else comes to mind I'll be sure to share.
*** edited to agree with the above poster - TAKE MORE PICTURES. Apparently I had less than 250. I know that seems like a lot - but I only had a handful of the Dream herself - and it's a beautiful boat.