A few things. My husband & I went to Disneyworld 3x BEFORE we had kids b/c we just wanted a warm, fun vacation. We've also been to Disneyland a couple of times.
First, purchase the Birnbaums's (maybe mispelled but Barnes & Noble will know)book for Disneyworld/land, whichever one you are going to. It's the "guide" book for the entire place. We did that as grown adults.
It told us things like to start at the back of the park when the gates open as there will not be any lines!!! Big deal especially w/ kids on a limited time schedule.
Secondly, I would get a good size backpack for BOTH you & your husband. Although character dining is fine, we didn't spend a lot of time in the restaurants. We brought lunchable type foods & found a nice area & ate several snacks throughout the day. Bring your own water. Who wants to pay $4+ for a bottled water? Have one backpack for food & the other for cameras, hats, SUNTAN lotion, souvinours (sp).
Third, purchase a 3 or 4 day hopper ticket. This will allow you to go to Magic Kingdom in the morning for the character breakfasts & then catch the monorail over to Epcot for the night laser & fireworks show. If you only had one park pass per day, you couldn't do this.
Depending on your son's age, he might nap while you visited Epcot as it's mainly a walk around place but each country represented will have a different food type. They also have some characters out at various times.
We didn't ever go in the summer so I can't tell you about the water parks except I'm sure they are awesome.
Hope these tips help. BUY THE BOOK! It's a must.