I'm with Thom. If I'm at work, my phone is on the desk next to me. If I'm at home, it's usually on the couch or coffee table. If I'm anywhere else, it's in a pants/shorts pocket with nothing else other than the cleaning bag for my sunglasses. As a result, I do not use a case for my normal day-to-day routine, and my phone is still in nearly pristine shape.
However, if we do something out of the ordinary where it is a little more likely that something could happen (say a day out at an amusement park), I pop it into my Incipio DualPro CF for some added protection.