Nice comp and B/W treatment. The color works as well, but can't match the B/W. It could just be my screen, but the blacks in the B/W are a little to dark for my taste.
Very nice composition and excellent detail in the highlights and shadows. I find the dunes work best in B&W and this seems to be true for morning light. Late afternoon light will offer some excellent color opportunities. Nicely done!
Love these types of shots, B&W dunes. They show the curvature and texture so well. I have one that's similar and arguably one of my favourite shots from that trip