Julie,
Tusker House is fantastic, and a really great buffet. When it comes to other meals at the Animal Kingdom, there are only two other suggestions from me. The first is Flame Tree BBQ. Yes, it is counter service, but in my opinion it is the single best counter service restaurant in all of Walt Disney World. The BBQ is really quite good, and the scenic seating areas, which are beautiful, secluded grottos, make the meal better.
The other is a table service, and a great meal as well. The Yak and Yeti restaurant has a nice, flavoful, and somewhat exotic and adventurous menu. The dining areas also really pop with a seemingly authentic (I have not spent any time in Nepal!) decor.
I would not choose to hit the Rainforest Cafe (located at the park gate), since it is outside the park. If I were to leave the park to eat, I would go somewhere else, like a resort hotel's restaurant that carried this theme for the day, like'Ohana or the Spirit of Aloha Dinner Show.
Have a magical (and delicious) vacation!