Dave,
I most definitely would not tell her that you want her to learn new techniques, even if it is true. She is working through her own fears and that will just make her fear being sucky in bed.
What I would do is to buy both books, the one for males and females and tell her that you did it for the same reasons that she bought the Kama Sutra stuff--just to try new things. I saw the female one in the library and thumbed through it and BOY did some of the suggestions get me hot and bothered. So I think you would have great success with it with your wife!
It had a little something for everyone..

HP