We've been to Disney World twice, for a week each time.
There's so much to see, that even with that, we haven't seen all of it. It doesn't matter how old you are, you'll enjoy it. The only bad thing is waiting in the lines, especially if it's hot summer days. The second time, we went in early June, and according to the people working there it was unseasonably hot. It was over 100 degrees each day. And of course Disney is one giant patch of asphalt, so that made it even hotter.
Back at that time, Disney still catered to those who were handicapped. For Raeden, they allowed us to walk up to the fast pass place in line to get on without having to get a fast pass, so she didn't have to stay out in the heat for any length of time.
They have since changed that policy because it was abused by family members of employees of Disney, who were given the handicapped passes at the front offices of the park. So now, they only allow anybody to get a fast pass which gives them a time to go to the ride...which, depending on how long the line is, is 20 to 45 minutes. The point is, you still have to stay outside in the heat that long. There aren't that many places to get into air conditioning that are close to the attractions. Raeden doesn't sweat, and overheats rapidly. Her face will be vivid red, and the skin around her nose and mouth is blanche white when this happens. The first time it happened was at Disney in fact. We had to leave really early that day. From then on, we carried a spray bottle with a fan to mist her.
When Disney changed their policy, and it was said that they would lose the business of those who were handicapped, the CEO said "They're just collateral damage."