Couple of things here. As someone posted before, the 2 Pandora rides are in the 1st tier of FP, while everything else is in the 2nd tier. If you're going to rope drop, I'd highly suggest getting your FP for FoP and hitting Na'vi River first as the lines have been much shorter for that than for FoP.
I'd also suggest that AK has become much more of a full day park (especially now with Pandora open). Pandora should take some time to explore by itself and Windtraders has some pretty cool merchandise you won't see anywhere else. There are shows your kids will love as well. Festival of the Lion King is amazing and Fights of Wonder is all my kids (7, 5, and 2 at the time we went) still talk about. Tusker House is a great character meal as well.
For my 2 cents. I'd rope drop Na'vi River, and hit FoP on a pre 10 AM FP. FP Safari next and then try and get into the 11 AM Festival of the Lion King. Lunch at Tusker House, and hit Flights of Wonder after that. You've got Kali River Rapids and then use your last FP on EE. If you're not into any of the animal trails, see if you can land a 4th FP for Dinosaur as you make your way out of the park. Even following a schedule like this, you probably wouldn't leave the park until 4 or so. If your kids spend any time in the Boneyard, it might make sense to grab dinner at Flame Tree, hit Tough to be a Bug and just stick around for Rivers of Light at that point. Having your kid do Wilderness Explorers is a great way to kill some time if you end up doing the full day.