I always get carried away for a month or two, when I get a new iDevice. I bought a Cover Buddy, and used it for a week or two, before opting to use the Smart Cover on it's own, and have been doing so for a while, as you just can't beat the iPad 2's feel when nothing else gets in the way.
As long as the screen is covered(Smart Cover), all is good. Scratches on the back are a minor thing, even if I don't have any yet.
It was the same story with all my iPhones, but in the 9 months that I've had my iPhone 4, the last 6 were with the device totally naked, as any case just took away the beautiful(visual & tactile) aesthetic. The glass has held up remarkably well too, with only the one hairline on the back.