Washington & Lee had a Panhellenic house prior to fall 2000 when the sorority houses opened up. It was a former fraternity house that had gotten kicked off campus (specifically Delta Tau Delta) in the early 90s. My impression was that it was another housing option for sophomore women (2 year living requirement at W&L and Greek housing is on-campus, so most Greek housing is filled with predominantly sophomores) and maybe some of the Panhellenic officers. Once they opened the sorority houses it became something called the "Delt Center" (uhhhhhhh) which was a house for independent men who didn't drink and would host non-alcoholic social events. I don't think I'd be out of line to say that that tanked miserably at W&L. Then, the house became the International House (a big step up for them, and they throw a lot of parties there now b/c it has facilities to do so just like the fraternities do) and the former international house became the Spanish language/culture house.
You can see a lot of pictures at the house here:
http://ihouse.wlu.edu/
One of the things I wonder if the IHouse will start doing is getting a cook like the fraternities do... I am not sure, but part of me wants to say that Panhellenic may have served meals there when they had the building.
I can't really say much else about it than that it existed and was basically a holdover for before they had houses. There was also an authorized "Panhellenic Suite" in one of the dormitories at that point too (and all the sororities had suites to store their records/materials as well). I'm not sure how the suite and Panhellenic house differed.