Contrast between cloth and skin

A design element that has always intrigued me is the contrast between cloth and skin. Many designers have used this contrast to draw attention to a specific area by using the negative space in the cloth. When this highlighting is done well it makes the garment pop. On the flip side if done without class, it degrades. The more common placements of revealed skin are: back, chest, and upper leg. I have included a series of shots from vogue’s website. What part of the body do these outfits reveal? Why did the designer choose that particular area over another?