The "gorilla glass" is part of what made me buy the phone, I don't cover the screen and sometimes use sunglass cleaner on it with a microfiber but that's about it.
I have a collection of Oakley glasses and carry cleaner with me, i use it once in awhile on the screen.
I have also used LCD screen cleaner on the phone and my laptop which works well also.
I clean it all the time because I already carry a small lens cleaning rag in my pocket for my prescription Ray Ban sunglasses and my regular eyeglasses.
When I first got the phone I did it a few times a day, now I never do- ever. I found that when I walk around with it in my pocket (front left with screen facing towards me for protection) the movement from walking cleans for me. So every time I take it out of my pocket its all clean.