Almost all of the old Greyhawk adventure locations have been revisited in the RPGA Living Greyhawk campaign. 500 or so modules in that campaign (between regional adventures, core adventures, interactives, etc.) using the 3E/3.5E rules.
Personally, I think the Return to the Temple of Elemental Evil module was the best of the "published" Return modules. Yes, there are various things in that adventure that don't appeal to everyone, but the module was the first 3e Epic (level 4 -12+) adventure. More importantly, it has the best support for any published module. The bullentin board on Monte Cook's website has tons of suggestions for GMs running the module -- I'm amazed that no other published adventure has a comparable GM advice section.