Thank you, Stan. I've decided to stick with the D7000 for now. I'm heading to Yellowstone in October and will see how my new lens, Nikon 80-400MM, performs there with the camera (I guess it really is my performance I need to check). I've already tested the new lens on the D7000 in various lighting conditions (outside) and both seem to be holding up well.
Again, I appreciate all the input from everyone that responded. It was incredibly helpful.