An Update! Brightened things up just a little bit, re-did the foreground, increased the density in the back trees somewhat, re-did the background hills surfacing, and most important left the water and clouds alone! This one is likely finished now as another rough but promising scene is coming along.
Thanks everyone for your suggestions and encouragement.
Dune: The bright sky is a combination of increasing camera exposure, positioning the sun just out of camera shot on the left, and an increased haze density.