we have so many good encounters with various characters it is hard to limit the stories, but i would have to say that two stand out more than the others.
firstly, we were at the meet and greet area at toontown, the princess area, and sleeping beauty was held up and didn't come in with the others. well the lines of people all stayed around waiting for her, one younger teen who was mentally challenged was waiting, and was pretty talkative, the mad hatter was there and he really did a good job of entertaining her, without ever seeming bothered or patronizing to her. it was really sweet, and my dw and were both touched, almost teary, to see him treat her so tenderly. i still regret not sending a letter to higher ups.
the second time was at the gg in epcot. we went to eat at offtime, in the afternoon, and were one of maybe five tables in the whole rest. mickey, minnie, chip and dale spent so much time with each guest, sitting down at tables, drawing and writing on children's menus and having as much fun with us as we all were with them. if you can hold out to eat at a character restaurant until between lunch and dinner, 3 to 5 in the afternoon, i think that you might find it to be most rewarding.