Thanks for the comments, critiques, and encouragement guys!
Ok, because you ask so sweetly, I have jimmied these up along the lines suggested and post the horizontal version. I have a slight problem with this composition, which is that the stone is not as prominent (further from lens) as I might like. I felt when shooting, that one strategy to leverage was getting the stone "in your face" and for the vertical comp, I was literally on my belly; wanted to include the sky for drama at the time.
I also toned down the crunchiness in the sky here in these two versions (Stone 6). But I will ask, is this a stylistic preference (artistic license) or something more fundamental and subtle? Part of what I hear is that you think the rocks have enough drama without adding to that in the sky, but FWIW, while I went for drama, I did take precautions to smooth things out in the sky. Curious about the origins of your concerns.
Finally, I did tweak the other three according to suggestions made in this thread; if there's interest I could post the "final" results. Maybe I will anyway, just in the sake of interest.