How'd you get your wife to play WoW?
We don't play WoW, but my wife does play Lord of the Rings Online with me. Actually she plays it a fair amount more than I do. I think MMORPGs are more likely to appeal to women than other video game types, due largely to the social aspect of it. She was already in the video game "door" when we met; she owned a Wii, and had more games than I did at the time. Some time after we got married I had her try out LoTRO, and she immediately took to it. Recently she took to Mass Effect and played that all the way through once, and has a 2nd character she's played partway through on, and is looking forward to Mass Effect 2's release tomorrow.
I think it's mostly a personality thing. Some women like video games fine, some can't stand them, and some are somewhere in the middle and can be swayed one way or the other, some will never play anything more than casual games, some will play anything at least some.