Only the first 3 (WG4 as part of campaign-play, WG5 & 6 as one-offs). I owned WG7 and 8 but never ran them because they were terrible (especially WG7); the latter (2E era) ones I never even bought -- I scanned them briefly in-store and could tell they weren't anything I wanted a part of. My opinion of post-Gygax Greyhawk is pretty well-known around these parts
P.S. Do people who have played "Maure Castle" in Dungeon 112 get to check WG5?
DM'd WG6 -- Isle of the Ape, as a one-shot, converted to 3E. Complete with scale dinosaur models, paleontological posters on the walls, big 8" King Kong toy, etc., etc. I went to town on that baby. (PCs were lost in the Spheres of Thought, btw.)
You probably know that the projected renumbering for WG1-3 was actually published in the adventure list of the Greyhawk '83 boxed set.
WG 4 played a big part in my pre 3rd ed campaing, and I always saw it as an underated module. I have been somewhat amused about how prominent the old imprisoned god has gotten in 3rd ed (though I am coming to regret it, but that is another thread).