Hi Scott,
What a great start to this scene. I really enjoy it, how long have you been tinkering with TG?
The one thing I could suggest is colour variation in the models via shaders. It's actually pretty easy to do so long as the object itself isn't broken up into to many parts that could be merged. Also some transparency to some of the leaf models might help them pop.
The rocks could use maybe one more (smaller) scaled version merged in to Highest Raise with the Merge Shader to give the appearance of scale variation.
Aside from those things there isn't much to add except that this is one of those renders (the way lighting is set up) that may really benefit from Path Tracing with the foliage shadows, especially internally within the pops which would probably help define depth month the pops.
Great work, and can't wait to see more from ya, you seem to be on the path to success.