I can speak only of our trip in 1996, when we brought then 20 mths old Kyle.
It was a terrific vacation. We went on HIS schedule. We went to the parks in the early AM - back to the resort for a nap, and then back each night. We had plenty of snacks - cheerios, crackers, and plenty of water with us at all times. We brought our stroller from home, so he could recline and take a nap if needed.
The resorts let us "borrow" a life vest for our entire stay. He loved the pool! We went to Chef Mickeys for breakfast one morning. Under 3 can eat for Free - so it was nice to take him to buffets.
He loved the rides, but was restless during the shows. We did do the Baby Swap for Space Mountain and Splash Mountain.
The one thing we noticed was how nice everyone was to him! It really was a fun week.
(9 yrs later, he still loves Disney!)
Catrin