I've always gone caseless and screen protector-less. I've dropped my iPhones twice in the last eleven years (once while lying on a gurney in the ER so that one really doesn't count, and once while cycling, after which I learned to make sure the iPhone is angled down the side of my thigh rather than the front, while wearing shorts with shallow pockets).
I guess I'm just fairly careful with my gadgets. And I always have AC+, just in case.