I like Avatar. Given Jim Cameron's history with theme park attractions - T2:3D at Universal - I expect to love the worlds of Avatar at AK.
The sequels will not only take place in the same part of Pandora that the first movie focused on, but on other parts of Pandora, and on it's moons. At least part of the sequels will be entirely undersea.
Given that this is not just going to be a single attraction, but a whole new land at AK, I expect there to be at least three major attractions, rides and/or shows, one from each movie. And of course, since it's Disney, there will naturally be a carpload of merchandise available, and I expect to see a Na'vi Mickey and Minnie walking around at some point.
First prediction: Jim Cameron will want a Hometree in the new land that dwarfs the Tree of Life, and Disney won't like that one little bit, because the TOL is the park icon and a huge technical achievement in Disney's history. Who will win, I don't know. But it will be an epic battle.