My first two completed 20-level 3.5 campaigns, Wing Three and The Kordovian Adventurers Guild, were both set in a modified version of Greyhawk; in the first one, the PCs' headquarters was actually in Greyhawk City. Now I'm running a completely homebrewed 3.5 campaign of my own creation, but one of the players in that campaign is also DMing a 3.5 Greyhawk campaign called Ghourmand Vale, in which I get to be a PC for a change. All three campaigns are set on the same modified Oerth, the second campaign taking place roughly 20 years after the first and the third campaign talking place immediately after the completion of the second.
Johnathan
Johnathan