I'll second the Amaray cases.
I'm very picky when it comes to DVD cases. I picked up several cheap ones to test at CompUSA a while back, and wasn't happy with any of them. I don't think it looks professional to give someone a disc in a flimsy, hard-to-use case.
The Nexpak Amaray case was the US industry standard. (I've been seeing some different kinds recently.) The Amaray has a very disc-friendly push-to-release hub, and you can get an extra "leaf" or "page" to hold a second disc as well.
Nexpak also came out with the Amaray II, which isn't made of as stiff a plastic. It's OK, and you can also get an extra "page" for a second disc. I prefer the original, however, it's sturdier and the push-to-release hubs on the original Amaray case and extra leaf work a little better IMO.
(One way to tell the difference between the Amaray I and II in pictures is, the "tabs" or "hooks" to insert the extra leaf are in different places between the two. On the original, the tabs are on the inside of the spine. On the II, the tabs are between the literature clips, at the inside edge of the front cover nearest the opening.)
BTW, I didn't like the Nexpak Alpha cases I tried, it was too hard to remove the disc and you ended up flexing it quite a bit. Plus, the single divot to slide your finger underneath to pry the disc up -- my impression was it just encourages people to touch the disc surface. The Amaray cases, you just push the hub and the disc pops up.
I get my DVD cases locally, but you could use Sleeve City or google "Nexpak Amaray"... Whatever you do, try to inspect before you buy, or look at some retail DVDs with cases you like, and try to get those... Anyway, that's my 3¢.