If you want to get the full benefit of the organized "program like" childcare programs, I would wait until your youngest is three going on four. From our recent experience, thought the 3-4 program could potentially be a little overwhelming for a young 3 or shy child. We went this May with a 5 year old and an almost four year old. Both kids enjoyed laying on the mats at night and watching movies/napping so we felt ok leaving them to enjoy some adult night time stuff. And, that alone was really worth it!!!I could not of enjoyed myself if thought they weren't safe and happy... I still peeked in a lot. On the sea day, my daughter wanted to spend most of her day in the program. She's 5. My son (3) wasn't so interested so he spent most of that day in the Mickey pool with his Dad. He isn't too in to the characters other than Mickey so simon said with Snow White just wasn't his cup of tea. We are trying the seven day next year, and I think my kids will benefit from being solidly in the middle to older ages in their groups. My son will be close to five, and my daughter 6 1/2. I think my daughter was a bit miffed she couldn't participate in some of the princess stuff they had for the four years olds. However, I think going at any age has its benefits. Both of my kids have toured Disney World when they still wore diapers, but we had a lot of fun and great memories. Just saying that I think being a little older allows the kids to perhaps enjoy the organized programs a bit more. My three year old did LOVE the dolphin experience at Blue Lagoon. Also, both kids really enjoyed the shows at night. We did the shows together and then had late dinner (as we all are night owls). Two nights they ate with us, and two nights we got them food before our dinner and they went happily to the clubs. We thought it was better to enjoy the shows as a family whereas sitting thru a meal would not be the highlight of the trip for them. Though, the staff at meals really do go out of their way to be nice to kids.