Thierry, Francois,
I updated the image above by bringing back the exposure on the trees. I had previously purposely brought it down to emphasize the amphitheater. But looking at it again I think it does look better with the exposure a little higher.
Also today's higher quality monitor's have much better brightness that brings out details in shadows a lot more. Looking at a few monitors around the house, I see the image is poorer on less bright monitors.
Cropping, I don't think is an option as the purpose of the photo is to show the amphitheater in its forest kind of setting.
Thanks