It's been great to read the discussion around this after coming back from a busy weekend. I've been thinking about the points made in this thread for some time.
This is a picture I had been playing with for weeks. I have a crop without the sky at all and a version with the sky. I also have about 6 different versions of processing done with this, but eventually decided to release this one as the final version.
Cropping the sky for me was a tough issue to confront. I can see the merits of the crops posted, but for me, the composition of the clouds and their tightness closer to the horizon led me to leave more space in the sky visible. I needed the clouds to be able to breath, but like some suggestions here noted, it upsets the traditional rules of composition. The crop I came up with felt the most comfortable to me, but it's encouraging to me as a growing landscape photographer to read similar discussions.
Without the sky, the picture follows the rules of composition closer, but in the end...how could I leave out a sky like that?