Lot's of good bikes out there now to choose from. To narrow it down a little, what, besides two up, are you looking for? Two up for long distance? Sport touring? Ability to carry stuff, comfy and handle? Cruiser out of the question? Like dual sport styling? Any brands you wouldn't consider? Price range? Also, as others have pointed out, might the bike chosen end up being a "starter bike" for your girl to end up learning and riding with you on?
Personally, not that it matters, If Ducati came out with a new ST with the 1098 engine, I think I'd be there seriously thinking of trading in a BMW K1200S.