I used to have Dreamcast games in slim cases (would modify the artwork to make the spine half-size), but I ended up running out of slim cases, and after finding out I could go to Blockbuster and get free full-size cases, I no longer had a need to use slim cases. Plus they just look better in full-size.
I also had Saturn games in the slim cases for a while, but again, I just preferred full-size.
