Thsi is what I would do
Stay at WDW value resort like Pop Century or All Stars, we stayed at the ***
Do dining plan for sure

, it saves a ton. If your DS is an adventurous eater you may want to put him on as 10, otherwise he will be relagated to eating off only the kids menu unless you are at a buffet restaurant. Unfortunatley for some odd reason the kids meals are very dull and uninspiring. At Pizzafari they don't even have pizza on the kids menu! (or at least in 05 they didn't) This will cost you more but he'll be happier. You can only eat so many hot dogs, chicken nuggets, and dishes of mac and cheese
Once there park your car and use their transportation it's a lot easier, I have done it both ways and their system is effiecient and cuts down on transportation time.
Get park tickets ahead of time. With park hopper and water park and more if you plan to do a water park or Disney Quest arcade.
Getting all these thing ahead of time means you only have incidentals to worry about when you get there which makes for a much less stressful trip.
PLAN PLAN PLAN

. If you don't you'll find yourself going around in circles. My sister didn't and when they went to Animal Kingdom they literally kept going in circles (every time they tried to get somewhere in the park they ended up at the same place. It seems my BIL can't read a map

) and never had time to do the Kilamanjaro Safari, which was the best thing at the park when they went. We planned out what park we were going to on what day during our trip and this made it easier. We weren't trying to decide where to go every day and it helps when making ADR's. If you plan on spending all day at MK then you know to pick a restaurant at MK
It's hot in the summer stay hydrated

. Use the snacks in the
DDP for beverages too. We found we didn't really want to eat a lot because we were hot, and I put fruit snacks and bags of goldfish in my bag for the kids if they did get the munchies. Of course you want the occassional Mickey ice cream bar, but it helps in the drink department to use your snacks
Take advantage of the fast pass. It is very helpful when the weather is hot to utilize those as much as possible so you don't have to wait in long hot lines. Trust me it's not fun

You can only get one ride at a time. Once you have used your fast pass you can then go get one for the next thing you want to go on.
Do water parks in the morning. By afternoon they are packed and I didn't think it was very fun once they got crowded. It was hard to find even an inch of free water space. I thought the pool was better.
Lastly read as much as you can, so you know what you want to do when you get there. To make your DS more involved in the planning get him the Birnbaum's WDW for kids book. My DS was the same age when we went and he absolutely loved reading this book and knowing ahead of time what he didn't want to miss and what he just didn't want to do. I know a lot of people don't like the Birnbaum books but I have found them very helpful, even if they are done with the help of D. It helps when you get to the parks to have an idea what attractions you really want to see, so you make sure to do it before the day is over.
Oh! don't miss the night parade and fireworks at MK and Fantasmic at MGM. My DS loved those! They are amazing.
Have a great trip
