On my early morning visit, I saw Dinosaur with virtually no line and the first show of Festival of the Lion King, had breakfast, did some shopping and left the park. Start in Dinoland USA and work your way around. If you want to cool off, go to the River Rapid ride. We went first thing in the morning and since there was no line, they told us to stay on and go again. They were going to let us go again a third time, but by then were were soaked.
Animal Kingdom is well worth it in all aspects.
Just be prepared for the heat. There is lots of walking and very few short cuts to get from here to there. This is the park to bring some of that extra camera equipment to take close up and long range photos. In addition, some folks have found binoculars useful for viewing the Tree of Life and the Aviaries. Careful not to bang yourself in the head with your camera.