What we have here below is a PAL Dreamcast game, to be exact, it's Tech Romancer and as you can see the case as well as the manual are pretty thick, but how does it compare to the JPN/USA packaging of DC games?
(http://i.imgur.com/TlVaWBx.png)
I like the fattiness of the PAL Dreamcast games whereas now the games don't even come with a manual any more (a pamphlet at the very least) and (still) with a BD/DVD case (BD = PS4 on blue / XO on green, and Wii U on a blue DVD case).
JPN DC games come in a standard CD jewel case - I know what you mean but I actually prefer it, the PAL games take up so much room.
I think US games are slimmer but fatter than a jewel case, I forget.
USA games use standard jewel cases.