Well, you have to decide on one "ideal" or "avarage" listening position in your room, probably somewhere between your and wife's couch -- you can be as ego-centric as setting your seat as the listing point, or the other way around. LOL At any rate, however, some compromise is in order. The physical "center" of the room does not matter; what matters is your avarage listening position, which may or may not be close to the center of the room.

Cheers!