Hi,
Since the release of 3e, I have run several games:
An FR game which started with 2e in the Bloodstone Lands over 12 years ago which shifted to Greyhawk and currently moves between the two settings.
A Freeport/Greyhawk game using Nyambe for Hepmonaland.
A high-level game set in Greyhawk with planar adventures using Planescape.
We are about to start another FR game in the Bloodstone Lands, but may end up using Eberron instead.
Before 3e, I have run games using Al-Qadim, 1e OA/Kara-Tur, Spelljammer (twice), Planescape (twice), Dragonlance and two homebrew settings.
Cheers
Richard