Those ages are so magical for characters. (That's why I always encourage people to take their children to WDW the first time when they are small....it's really the only time you have pure innocence and fantasy with the characters).
Personally, I'd vote for a Pooh meal. I find the Crystal Palace way too rushed, so if you go for Pooh and have a car, drive over to Olivia's at OKW. The food is okay, but the character interaction is unbelieveable because the restaurant is smaller than most. Pooh always tends to spend more time with small children like yours, and at Olivia's he has the time to do it.
Otherwise, I'd do Donald's Breakfastasauras in AK. That's lots of fun and lots of the characters.
If you want a resort breakfast, do Ohanas at the Polynesian. Last time I went, it was Minnie, Goofy, Chip and Dale all dressed Hawaiian themed....and they did parades with the children around the restaurant.
Enjoy your trip....the look of their little faces will be in your memories forever, trust me!