I think the colours/ trails in the sand work well with the claws in the second one. I like the rocks in the fourth one, but I find myself wanting to rotate it 180 deg to see if it looks better that way.
Mike I know what you mean about the rotation. I often rotate an image to see how it looks, if it would improve. I always end up setting to the original as that is what I first sa and somehow it always dominates.
Certainly if you draw or paint, by turning the image upside down, it is a sure way to see if it has depth.