I agree with the above, but I also find it helps to move the genre out of "D&D". So, if you're wanting to try something else, do a game that doesn't mesh immediately with the "group of dungeonpunks adventure in a semi-medieval world with magic." Do something cyberpunk. Or modern investigation. Or space opera. Something that is NOT D&D-ish. They'll like carry a lot of habits with them, but the distance will help make the differences more reasonable.