When you and your niece go to AK, don't miss Rafiki's Planet Watch. Go to Conservation Station (after doing the Safari first thing in the AM) which is next to the Safari, take the train back there and see what animals/birds the Disney vets are operating on/examining, starting usually around 10 am or a little before and lasting for about an hour, sometimes two, depending on what they are doing. This happens every day except Wednesday. While you are there take a look at the live spider/reptile/large bug exhibits...and the butterfly room. Experience Grandmother Willow"s, "Sounds of the Rainforest" and gently interact with some of Disney's smaller creatures brought out every half-hour or sometimes hourly...I especially love the little hedgehog when he is brought out, but there are many other amazing creatures. A Disney animal person brings them out and talks about them and answers questions. Also back there and outside the air-conditioned building is "Affection Section" where you can pet/groom the goats and see canny chickens that cannot be caught, though little hands try mightily lol...btw Affection Section has a place to wash your hands before/after you interact with the animals.
I didn't realize I was going to post so much...but I just saw so many people saying AK was their least favorite park...and I guess I reacted a little bit defensively. What I mentioned above is just a tiny fraction of the experiences that are available in AK. If you have the time to really find many of the secrets of AK, it can be a fascinating park for every age...but not all venues are for every child or adult. Don't miss the bird show though, at any age...and visit the tigers and bats the last hour before close. Attend the "school" in Harambe if you have time.
Go slowly and savor AK...alternate outdoor activities with air-conditioned shows and shops...talk to the CMs found on the exploration trails. They have lots of stories to tell if you have the inclination to listen. That's how I heard the tragic tale of the komodo dragon and the easter bunny...close down the park by walking back to the front with the last CMs to leave the tigers/bats area, chatting with them about what they do and why they choose to do it...and then go to Beaches and Cream for your evening meal...what an absolutely wonderful day you will have!
My least favorite park anymore is MK when it's crowded. People get rude when they get crowded, especially where their children are concerned, which is doubly unfortunate. Give me any park besides a crowded MK.