It depends on what she wants.
Here is what I have discovered:

American Wisteria - blooms early in its life (2 year old plant) the blooms are about 4 inches long, and are not really fragrant.

Japanese Wisteria - Blooms late in life (3-7 year old plant) and has fragrant blooms roughly 8 inches long.

Chinese wisteria - similar to japanese wisteria for the most part.

This is a very highlevel description of the blooming of the wisteria types. there is a world of other info out there about the differences (eg. which way the twine, what colors you can get), but for the most part I stayed away from the american kind, because I am patient enough for the "bigger fireworks" if you will.

I think the American variety Amethyst Falls is much prettier then the Japanese varieties. It doesn't have any scent though. It just depends on what you like.
Karyn