Personaly I hate bumpers and so on. It's smart for people who drops their phones all the time (my girlfriend) but come on it's a beautyfull phone.
If you buy a lamborghini gallardo would you wrap that in bobble wrap just to avoid scratches and other stuff in case of someone crashes into you?
I got an insurance, and thats to take care of if anything happens to me, my phone, my mac, my lambo (toyota avensis

), and all the other stuff i own.
But I love to see how stupid people are "I've got the macbook because I'd like to have a slim laptop", and they ruin that by clamping on a large piece of ugly plastic.
I have been working in a metal workshop the last 6 months, and i have no protection on my iPhone at all. I've used it with oily fingers, metal all over me, while im welding, grinding and so on, and i havent got a scratch in it.
Out of that I can only say, take care of your stuff, and all the other stuff is not something you need.