Curious if anyone has played a campaign in either of these settings. I think after my current game that I'll may be DMing for my small group but wanted to break away from the standard high fantasy setting.

I have not ran in either, but I'd definitely be interesting in doing so. I might even run a PBP game in one or the other at some point, but I'd definitely have to read up on the lore for whichever one I chose.

I really would like to play a Thri-Keen... perhaps a ranger using some Brutal axes.

Eberron is an awesome setting, though sadly with 4e it mostly became a place where everyone could just play warforged, but at least it broke up the monotony of having half of every party be dragonborn. I've not played in Dark Sun yet because normally I focus on high fantasy but if given the chance I would.

I fully recommend that everyone play at least one Eberron game at some point though.