Good looking so far, nice image!
PG has a good suggestion I think, it would add an extra interest to the picture.
Personally I think you could maybe even better add more "volume"/vertical features to the clouds. From fore- to background the whole cloudplane looks a bit flat. I would be nice to see some vertical outcrops of clouds, like you can see in the links provided by PG.
You could this by adding an extra cloudlayer with some warp added to the cloudfractal.
However, extra cloudlayers increase rendertimes quite much.
Another approach, and more tedious, is to setup the warped cloudfractal and mix it with the original cloudshader using a merge-shader.
Martin