We went twice when DD was 3, as WDW was having great discounts that year and the inlaws wanted to go on a trip with us. They were great trips! We have taken DD, now 8, every year since she was 2. I would not give up those preschool trips for anything, they were my favorites of all my WDW trips. She was better behaved at WDW than at home at those ages, because she loved it there so much!. I also think that DD was more difficult on her age 5 and 6 trips, than in preschool- More walking instead of stroller and did not quite have the stamina for it yet, so she tended to get cranky here and there. By 7, she was doing open to close walking the parks without any complaints. I say go for it!