I am about to run Dungeon's Adventure Path, the Shackled City, in FR and I am on a quest to find all the resources I can on the setting.
I was planning on using Greyhawk, since all the gods listed in the adventures are from greyhawk, but I am a little more familiar with the realms, although it has been YEARS sice I ran anything there.
How long, you may ask? I started a 6-year FR campaign with the old 1e grey boxed set when 2e first came out. I then shelved FR due to the massive amounts of material that followed and have been using various homebrew/piecemeal worlds since then.