Italian Sportingoods in Vancouver, Ruger GP-100 for $475 brand new, if they still have any in stock. Last time I was in there they did. Me and my buddy both bought one. Fantastic guns. Same for the S&W though, they both warrant owning. If she's relatively new to shooting maybe stick with a cheaper gun and see if she likes it. Personally I'd stay away from the Taurus at all costs, some people have no problems but if you do you'll have fun getting warranty or service on it. If you want a gun that you can shoot the hell out of and ten years down the road sell it for more than you paid for it today buy a Python! The Ruger, though, does have fairly small grips on it and she may like the Rosewood inlays.
Best advice though, get her out to the gun store to hold them and tell you what she likes and feels comfortable with. If she "likes" it then she'll be happy with it and enjoy shooting it, if she's kind of on the edge, even if it's a superb gun, she won't enjoy shooting it.