The standard jewel case is what I still use for radio distribution. Their libraries are typically sized for standard plastic jewel cases and I want to be sure mine get a chance to stay in there! I do like some of the other packaging and would certainly drop that case if I didn't aim a significant portion of each manufacture run at radio.

I am miffed by the obvious "shelf damage" CDs can take, after being lugged around from festival to festival. I also, mark a cracked case down, even though the CD and the contents are good. I've not had actually broken cases.