You will find that each park has a different feel to it, but that no matter which park you are in, there will be plenty to do.
Here are the things I would advise you on (i.e. my screwups from our first trip).
1. Get to the park early. Since you are staying on property, one park will open even earlier on that day, but most in property people plan to go to that park, so it will get crowded as the day goes on. That being said, eat breakfast either on the go or in your room (some great places to pick up a treat as you walk into the parks or take a pack of breakfast bars, fruit and pop tarts with you and skip breakfast out all together if your family will go for it) and be at the parks when they open.
2. If you have PS Character breakfast reservations, make them either really early (and you will be allowed in the park before it opens) or really late for breakfast (where you get the best character interaction because most people have moved on!).
3. Use Fast Passes. They really do work and the earlier in the day you get them, the less time you will have to wait until your "window" to ride. You get an hour time window to go back and ride the ride, and being there right at the time is great, but if you can, go by and get another fast pass for a different ride BEFORE heading into the first one. That way you always have time ticking on a fast pass in your pocket which will save you SOOOO much line time on the busy days.
4. As others have said, pick your rides that are MUSTS for each park and plan your day accordingly. Not time wise necessairly, but location wise. Know where the rides you want to hit are located so you can get to them all in the least amount of time.
5. Go and see at least one parade while you are there. If your son likes it, go to the others at the other parks! My children love the parades so we take that time while staking out a spot to rest and to have a snack. Also, make sure you have a spot picked out where you will be able to see. When the parade starts, you will be amazed how many people will suddenly appear and will put OUT so that your line of vision down the street is suddenly gone. You will still enjoy what is right in front of you, but part of the charm to me is having a "bigger" view. If you can get yourself on a corner where the parade is coming at you and then turns then you will be in great shape. Or try the trainstation or on the curb in the entrance area (inner circle of the courtyard when you first go under the train station and enter the park - on the curb where the flag pole is) are all places I have had the most luck with my children being able to see.
6. Go and see the evening shows - Wishes, Spectra Magic (which is a light parade at night), Fantasmic and Illuminations. If your son loves fireworks and other special effects, they are all fantastic!!!
7. Most importantly, you won't see it all in 5 days, but you WILL hit all the rides you are interested in. If you get tired, slow down, stroll over to Downtown Disney and shop. Go see a movie. Take your swimming trunks - heated pools are a great way to break up the grind of the parks. Have a Mickeybar (ice cream) and people watch. (ok - I will admit that I am working on this one myself
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Good luck and if you come up with specific questions, please ask!
Our DD was 7 the first time we went, and it was a great age. She was young enough to feel the magic, and old enough to be able to walk around and enjoy some things like Epcot, that she would not have otherwise.
