I agree with Brian, I like the drama here. The high contrast plays up the sensuous dunes and I like the way you contrasted the smooth dunes against the rough textured hills beyond. The tendency for most is probably to focus on just the dunes as they are so compelling, but the contrast of forms gives each more meaning. The B&W simplifies that contrast even more, down to the basics of what is important in the shot.
From your images, Derek, I've got to say I like these dunes better than the 'other'
Death Valley Dunes...this is a magnificent shot. Extremely well composed, with
fantastic variety of light, texture, and tonality.
Brian