Scary rocks 2

Continuing the painting assignment, I've put together some digital color roughs (still have to paint more the old fashioned way, but this helps me visualize quickly):

If I wanted to fiddle more with these I'd make the sky brighter in the 2 monochromatic ones, which are literally the multi-color painting desaturated, then with a few mouse clicks set so the achromatic lights and darks translate into the lights and darks in monochromatic. No re-painting was done, as I said just trying to quickly visualize, since I need to repaint by hand anyways, why waste time?
I do quite like the multi-color and I'm hoping the final will mostly be an improvement on that. Also after a demo in last weeks class I'm considering switching back to acrylic, only this time using a transparent method. I've always painted super-opaque with acrylic, but transparent-style painting with the layering ability of acrylic (as opposed to gouache which often gets messed up when you paint over it again) is tickling my curiosity...

EDIT: Re-uploaded the monochromatics with new versions where I fiddled with the brightness/contrast setting to get rid of the murkiness.