In addition to the TPU case that comes with the phone (which I didn't know about, either), I got the Sandstone case from the official store.
It is awesome! Totally great feel to the Sandstone texture, grippy, solidly fits the phone, and all the buttons are EXPOSED (which I find to be ideal) as well as the top and bottom of the phone. It has a lip so the screen doesn't touch when face-down, but it's very minimal. I really love the feel of the phone in this case.