Well, I've run a lot of Dark Sun games, and I sort of used the following "Changes"
1) All of the city-states were run by high-power defilers who were also dragon kings. However, while they were old (quite old) they weren't Champions of Rajaat or anything; if a PC became a dragon, he could have templars, too, and start up his own city.
2) Every type of magic was "evil" - clerics were just as likely to be in the Veiled Alliance as everyone else. Psionics were everywhere, though.... however, they weren't necessarily embraced; someone with a wild talent often kept it secret because it was embarrassing.
3) I ignored the entire prism pentad series.
4) I'm fond of the DRAGON/DUNGEON DARK SUN remake, with the exception of the psionic races being included. I like how they set up the new campaign.