So, I need to buy a case for my shiny new iPhone 4S. I want a case that covers the sides/back, not the front, and is either black or white. Anyone know of a good one? I really like the design of the Incase Slider, but I've heard it's brittle and cracks easily. Anyone had experience with the Incipio NGP? My fear that I have with a lot of these cases is that I've heard that dirt/sand/etc scratches the side band really easily..