I don't care what they do on the back and front, just don't change the spine midway through. Although saying that, being from the EU, I hat the EU ps1 and ps2 spines. Really boring, prefer the NTSC spines.
Conversely, I don't like the NTSCU GameCube spines, as the location of the system logo is on the bottom rather than the top. My favourite gamecube cases are the NTSCJ small boxes, small logo. Dinky, and nice.