Some personal insight for you. I worked for Disney Vacations for several years and as a Mom. I have a 2 1/2 yr old and 1 yr old. We have not taken them since they tire so easily.
Disney World is much larger than Disneyland. A 2 yr old can go part of the day but would need a nap by early afternoon.
If they will fall asleep in a stroller thats great, and some do but if they don't you might want to plan a nap time at the hotel. Some families will take time out at the hotel for some afternoon swimming, while your son is taking a nap. And then so back to the park for the late afternoon evening.It will be cooler and you can go out for dinner everyone refreshed and ready for the evening. IN the Summer the parks don't close till later anyways, and you can enjoy the fireworks and parade too. We thought about going so we could get the kids in for free since they be under 3 but they aren't going to remember it. And many rides are too big for them so we decided to wait a few years when it will be forth the expense.
I hope this helps. Another thing if you go and take him
I would reccommend a Character Meal. YOu eat at the restaurant and the Disney characters walk around to each table signing authographs and take pictues with kids or adults. NO long lines.