I used to have the Apple bumper case on mine, until I realised it was leaving marks, like freckles, on the bezel, near the dock connector. So I took it off and have had my phone naked since then, except for a rear screen protector for when I place it on a table etc. Other then that I use no case, and it's actually been better off then when I had the case on! I'm careful with it so it doesn't get marked any further though, but I just like to keep my phone as it is rather then hide it away in a case.
Looking for a good price for the TomTom car kit now, since I've sold my Brodit case as I like the look and feel of the tomtom kit - it's just expensive for what it is, hence looking for a decent price on eBay etc.