The best protection with a thin case is probably the Mous case. It has a rigid structure to prevent bending, and foam to absorb impacts. They throw things off cliffs in the ads. They are expensive - it takes a lot of engineering and good materials to get that much protection in that skinny a case. But when you need the best, that is the first place I look for my tablets and phones.

Slightly less expensive is the OtterBox Symmetry 360 Case - still very good protection in a light package. (Otterbox makes other iPad cases that are even stronger, but they are also more bulky.)