For me, Dark Sun is defined by Brom, and Planescape by Tony Diterlizzi. The art is the setting. (and I love them both for it.)II think that is what a lot of the smaller selling settings lacked, a champion and face to put to the setting. FR has Ed Greenwood. Greyhawk is Gygaxian and has had many champions over the years. Dragonlance has Hickman and Weiss. Dark Sun? Troy Denning was the author of the DS Prism Pentad, but he is a prodigious author of lots of material in lots of settings. Planescape? Ravenloft? There is no 'go to' person for answers about what is the setting about.