Definately take advantage of the washer/dryer. We realized when we did laundry on that last trip that we packed way too many clothes. I will probably do a load of laundry every night and probably pack about 4 sets of clothes (mix and match some) for a 10 day vacation.
We also did gardengrocer.com and had groceries delivered. We had cheerios, diapers, baby food, bottled water and other snacks, food etc. It was a little more than what we pay at home, but really nice to not have the hassle. Get some lil ziploc baggies to bag some cheerios or snacks for the little ones. Gives them something to snack on throughout the day without having to try to find a snack. We couldnt find anywhere in the parks that had apple juice, so we get little bottles of those too delivered. That helped. Also, if everyone can take a carry on, that will help with eat kids taking their own backpack with their plane activity type things. My kids are 5,4 & 2 and will be 6,4 and 3 when we travel. We have coloring books, leapsters and a few books. We leave the favorite stuffed animals at home and let them pick something little the first day to sleep with! We do always pack another bag for souveniers but you can also have those shipped home and now that you have to pay for bags on planes, might be better to just ship them all home!
There are babycare centers in each of the parks that have small packs of essentials like diapers, wipes, pacifiers and even some snacks. They also have stuff in the hotel. We have had a child get sick on almost every trip and they have kids/baby tylenol, thermometers etc in the gift shops in the hotels.
FYI...if you have someone get sick, there are pharmacies that will deliver to your hotel. We had an ear infection show back up with my son last winter and it wasnt cheap to get a prescription since it was out of network, but sure was convenient.
Another thing....Sorry I am rambling....
We were never sure how much we would use the pools and ended up going a lot. Even in January, we went a few days. Anyways, they sell pool floaties in the gift shops too and so we bought those the first time (they were nemo) and take them back each time. I think we will get one of the Owners Lockers and that would be something we keep there stored.
There is probably more and sorry I got off topic..but I know what it means to travel with little ones and try to share anything I have learned along the way.

The best part is that since you have all boys, you dont have to buy princess costumes. I forgot our costumes at home in Sept and didnt have them for the Pirate and Princess party...so I had to swallow the cost and buy them for my girls. It was my fault for forgetting them. At least they got to wear them for Halloween!