Naked when I'm at home:
Got a $5 TPU case off EBay. Use the case and a front protector. As soon as I get in the house, I take the case off. I wash it every few days as well.
Here's the one I use. It's a compromise between an ugly otterbox and a hard plastic case. I love it.
http://item.mobileweb.ebay.com/viewi...d=320634078600
I have an extra one that I am willing to trade for a new or almost new bumper if anyone wants.
I rolled naked outside once and my car keys scratched the back of the iPhone 4. The glass is very prone to scratches, regardless of what Apple says.