Everyone wants to get Mickey's autograph when they go to Disney World, so the character meet-and-greet lines can get pretty long. Instead, I always book one of Disney's character breakfasts.
I usually choose based on my kids' current favorite characters so they can get photos, a hug, and an autograph while we eat breakfast.
There are usually about four or five characters, and they circulate around the room, so each one should pop by your table at least once during your meal.
These tend to book up quickly, so you'll want to make your reservation right when your booking window opens up (60 days before your trip).