If your little one is like our 20-month old, the characters were the highlight of his Disney trip. He ran up to each and everyone of them, hugged them and was thrilled to see them. He "led" the Character parade in the Character Breakfast at Ohana, with Mickey holding his hand.
Plan on her napping in the stroller. You can't count on getting back to the resort for naptime. (Once you see them starting to get sleepy, it's too late!) In each park, we found quiet places where he could sleep in his stroller. Bring a stroller that reclines, so she can sleep well.
My wife and I would split up from time to time in the park. One of us would go see the things that the spouse didn't want to see, while the other stayed with the toddler. (Nap time is a good time to do this).
We parked our stroller at many different places in the various parks, when we wanted to carry our son with us on a ride, and no one ever messed with it.
Animal Kingdom's Africa section has lots of things for little kids to do. For example, some Cast Members in authentic regional costume come out and play drums, tambourines, maracas, etc... They hand out instruments and let the kids join in. Africa also has drums set out, for people to drum as they please.
In Magic Kingdom, go to Mickey's Toontown!
Try a Character Breakfast. Ohana's is great.
That's all I can think of now.