Also be aware that a great place to meet some "rare" characters is inside the Animation attraction at the Studios. This is not published and not guaranteed, but every night we were there in May a whole whack of characters would come out at 5:00 and then there would be others at 5:20. These characters used to come out in front of the hat and their times would be published but now they are in the animation building. The easiest way to see them is to walk through where the attraction exits into the store -- this is an acceptable entrance to see the characters. You'll find a variety of villains and robin hood characters here in addition to many others.
Also, Brer Rabbit is now meeting in the front of Animal Kingdom many days. He hasn't done regularly scheduled greetings since I started collecting autographs in 1998.