When I look for a case I like to find the ones that have useful features over bulky protection. I am not in the habit of dropping my smartphones. As a matter of fact, I have always had single layer shells.
The HTC One S is one of the thinnest smartphones in the world with a 4.3inch display. One of the benefits to having such a thin smartphone is that you can use a dual layer case without it getting uncomfortable.
Color, style, protection level, are all things that people look for in a case and the selection can get confusing. Having someone who could show you the different styles, colors, and protection level would make life so much easier.