Hi Amy! YES, I have several ideas for you! My family loves the
Animal Kingdom, and I especially enjoyed bringing my children when they were toddlers and preschoolers.
There are two walking trails that I highly recommend. One is called the
Maharajah Jungle Trek and the other is the
Pangani Forest Exploration Trail. These both offer quiet strolls where you can see animals up close, on your own time schedule. In other words, if your nephew is really enjoying the gorilla, you can spend as long as you'd like at that exhibit. There are "field guides" available that you can use to spot the birds along the way. This is a great way to occupy your nephew.
Another fun place to visit is
The Boneyard. This play yard is full of fun. There are slides for your niece, as well as a large climbing structure. I'd venture to guess that you will spend a lot of time here.
All of Animal Kingdom has a laid back atmosphere, with peaceful trails and lots of space to walk around. I think the day will just fly by for you.
What a wonderful Auntie to spend the day with them at Animal Kingdom!
Enjoy,
Kaylene