If it is your first time to AK, I wouldn't look to do any tours or anything. You are better off just enjoying and exploring the park on your own, unless you plan on spending more than a day there.
With that said, we always make it a point to hop a train over to the Rafiki's Planet Watch, home of the Conservation Station, an air conditioned building that usually has a M&G or 2 and if your timing is good you might get to see them do a procedure on an animal from the animal hospital while they explain what they are doing and why and the Affection Section which is a little petting zoo.
Also, either on your way in to the park or just before you leave, spend some time walking through The Oasis.