I think this is a very good scene to spend time on.
start with some outcrops and bolders and such. Things just need to be diversified a good bit more. Also some color variation in the stone, looks like you are only using 2 colors. Generally most images in this forum are really good, but just lack lots of fine details (mine too). ITs tiring to do that, but its worth it.
Break up your strata a bit more with a smallish, scale PF.
Take your image into PS and do some post processing. Try to play with tone and color and contrast. See what you can achieve there so that you don't have to do all the work in TG, it would be faster to do anything that can be done in PS. The render is a bit flat now, but I know the info is there already, just bring it out more in PS.
Thats all I can think of at the moment.