:Welcome to the DIS!
We just got back, ds was one week shy of turning two on our trip.
He loved the characters. Wasnt too impressed with the princesses though

We did breakfast at the castle princess breakfast(Cinderellas Royal Table), he wasnt too impressed

Oh, well that one was more for me anyway!
We thought Chef Mickey's was awesome. Ds LOVED the character interation (Mickey, Minnie, Chip, Dale, Goofy, Donald Duck). If you dont mind leaving the parks, IMHO this one was the best. It is in the Contemporary resort, just a short monorail ride away from MK. We did it the night we did AK, as it generally closes about 5, so we had our adr at Chef Mickeys at 5, and didnt really 'miss' any park time.
We also did Crystal Palace with Pooh and friends (Tigger, Piglet, Eeyore,Pooh) Crystal Palace is more conveniently located, near the end of main street in the MK. If you dont want to take the time to leave the parks, it may be a better option for you.
DS loved both. I felt like the characters were less rushed at Chef Mickeys than at Crystal Palace, but the service at both was great and ds enjoyed them both.
You do not have to pay for an ADR, but you DO NEED THEM!!!!!!! I would call very soon and schedule your meal, we did ours at the 90 day mark.