You might take a look at the Antec NSK series. The appearance looks understated and classy (to me, anyway), they'd look good with black drives, and they don't have doors over the drive bays. Or the Antec Solo (a P150 without a PSU) if you want to pick a PSU separately.
The
NSK4400 is basically a SLK1650B with a different PSU and bezel, from the looks of it. SilentPCReview has some comments about the PSU
here if you find it interesting. It's too bad the 4400 doesn't have the front USB, Firewire and audio ports like the 6500 and 3300 do.