We love meeting the characters too! Here are some great things we have learned.
1. Make a customized autograph book -- the characters give your kids lots of attention and love to look at the book -- they really ham it up and point out their picture to everyone. Minnie Mouse sat down on the floor and looked at every page of DD's book, and signed it very sweetly -- dd has been in love with her ever since.
2. wdwautographs.com is a great sight for autograph info
3. there is a meet and greet at Epcot-- we met Mickey, Minnie, Donald, Goofy, Chip n Dale, & Pluto there Sept 06.
4. In Epcot, at the back of the toy store in England you can sometimes meet either Tigger, Pooh, Piglet -- often no crowd, especially if there is street entertainment
5. The characters really interact with you if you are "wearing" them - ie: hat, pin, t-shirt
6. In France, in the outside area on the on the other side from the shops, by the bridge (sorry I am explaining this badly) I have seen Belle, Beast and Aurora with hardly any lines because it is a tucked away spot.
7. If you are lucky enough to go during the Magical Beginnings at MK in Fantasyland, DO get there that extra hour early. It is wonderful -- there are characters everywhere, playing with children, going on rides, playing with eachother (Peter Pan and Captain Hook playing hide and seek, Alice and the Mad Hatter skipping about, Daisy and Minnie playing ball with kids, Mickey playing follow the leader). They don't do autographs , but play and interact. It was the best character interaction ever.
This is a great thread.