If you subscribe to Kenny the Pirate's character locator (about $10, IIRC), he has a listing of every character in each park. Each character's section includes info like where to find them, what hours they'll be available, interaction suggestions, and whether they sign. The one negative to the site is that the schedules are updated fairly last minute. (I think it updated on Saturday or Sunday morning for the current week, including that day.) That won't matter for what you're doing, but I found the site worked better used on-the-go in the parks than for planning before our trip.