Re: Naked or in a case?
I hate having a case on my precious baby. I also hate all the screen protectors. But it really depends on the environment around you, and your behavior. I am Egyptian, I live in Qatar. Since everything is quite here in Qatar I do not really use a case, or even a screen protector. I always keep a free pocket for my iPhone (or any other smartphone I had), everything else as keys, and wallet also tissue goes to the other pocket(s).
But when I travel back to Egypt for a short summer holiday, since it's a holiday and I get to spend more time out having fun. I always get a silicon or a plastic case for my iPhone to protect it, but that's a temporary case. I instantly stop using it once I land in Qatar.
It also depends if you have kids or not, and if their behavior too. If you had cases before where they threw / dropped your smartphones then you need an otterbox, not only a silicon or plastic case. If not, you should be safe.
Although I never use a case, or a screen protector I tend to keep my iPhone scratch free for as long as I own it. I had an iPhone 4S 2 years ago, it stayed with me for a year, then when BlackBerry 10 was introduced I wanted to give it a try so my mom decided to take my iPhone 4S... Now I feel sad for that phone, it is full of scratches, coffee stains and much more. Now that I am planning to move back to iPhones again I don't think I will use a case.
*I get crazy when it comes to scratches. I bought an iPad Mini 3 months ago when I was in a short holiday in San Francisco, but because I allowed my family to share it with me and they treated it carelessly just like everything else, it of course go scratched. One day later I decided to give them the iPad Mini, and get myself a new one that none of them was allowed even to touch...