Rob,
We must assume that you were inspired by your senses and judgement to position yourself and the camera for this unique image. I'm sure you were thrilled at the sight of man confronting the monolith! When you got home, you discovered a disconnect between what you remembered you "saw" and what the dumb camera recorded. One of the hard facts for many of us to accept is that the camera can't recognize humor and irony as we do! So now, one has to reproduce what you felt and what stirred your heart when you framed the scene. Actually you have a lot of tools to bring back what caught you when you made countless decisions to frame the picture in the first place.
So, I'd caution against any cropping at this stage of preparation of the picture, if it's not actually ready for printing. To my mind, (and if this goes against the grain of your natural sense of the build of your pictures, ignore my view), the tonalities, contrast and micro detail of the grass, pathways, clouds and water need to be allocated for your stamp of expression. If not, then isn't this just a snap of what the camera engineers allow to anyone?
The water, especially has potential to help define your key elements.
If you were already certain about the picture, I'd hold back and accept this presentation as your style. But right now, I get the impression that you might have more important choices than cropping, to bring out your man confronting the monolith!
First trust your framing and work on the elements ranking them according to your own wishes. Do what's necessary for the picture to express your imagination of this "theatrical stage" that you are "dressing" for public view. You have lights, texture, shading and more to allocate sparingly or generously to everything you discover. That's how pictures should be prepared after framing outside a studio!
Asher
Of course, if your position was limited by access and the dimensions of the image frame did not fit your composition, then, of course, crop as you intended when you took the picture!
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