Our girls were ages 2 and 4 on their first two trips to WDW. We've done every character meal over the last few years, but Chef Mickey's, Crystal Palace, 1900 Park Fare, Cinderella's Royal Table, and Garden Grill were the most exciting for them. I think CRT, Chef Mickey's and Crystal Palace would be the top 3 from this short list if I had to narrow it down.
As for the meals noted, you can only do dinner at Garden Grill, but if you go- ask for a table on the lower level. As for the other 4...we prefer breakfast to any of the other meals at these spots. And if you do Crystal Palace and/or Cinderella's Royal Table- I'd try for a pre-park opening breakfast. While the park isn't totally empty at that time, it's certainly not crowded either. Just love seeing the kids skipping up MSUSA with plenty of room to spare. We like the 7am slot at Chef Mickey's since you can have breakfast and make it to any of the parks in time for opening.
As for all of the others...the reality is that experiences can vary at all of these (even our faves noted above). Examples: Our experiences at Tusker House have us in no hurry to return- yet we know others still rave, we like Akershus lunch and dinner over breakfast and also over CRT lunch and dinner- still I prefer being the castle to being in Akershus, Cape May has great food- yet for the price I feel there should be at least 1 more character, we like H&V breakfast - the food-service-characters were all good- but I don't think I'd do the Playhouse Disney themed meal again until they offer 1 or 2 popular characters beyond the preschool set, and while we had great service and character interaction at 'Ohana breakfast- the food when we went left a lot to be desired. Still- these are just our personal opinions and experiences.