We all love AK and it's DS's favourite Disney park. Like DisneySteve, I always wonder how people can call it a half day park. (No offense intended Muffy, because I have seen many, many posters who think as you do. We're just animal lovers who think AK is a great combination of animals, shows, and rides.)
On our trip last year we spent a full day at AK and still didn't hit Rafiki's Planet Watch (probably two hours required for this attraction alone) or the Tarzan Show. Admittedly, we usually spend the last half hour at the park riding Kali several times in succession, and we also went on Primeval Whirl twice, but if your group is into animals there's lots and lots to do.
We ride Kali at the very end of the day when the CM's just wave us through if we want to re-ride, because after the first trip we're so soaked (even wearing ponchos) that more water just doesn't matter. However, we also put on a fresh shirt afterwards, and a complete change of clothes if we're heading anywhere other than our own hotel.
If you can get a PS at Breakfastasaurus before the park opens, I'd go with that choice. Otherwise, I'd get there at opening, do some of the big attractions, load up with a fastpass, and then go to breakfast at the last PS time (I think the breakfast is until 10:00, but I believe that's when they seat the last people, as opposed to when they clear up the buffet).
Have a great trip!