What does SHE want?
If she says she wants a bigger bike, and is capable of handling one, then surely she can (and probably has) done some research and knows what she'd like to sit, or ride, and buy?
Please remind the dear lady that she does NOT have to be flat-footed on a bike. If the balls of her feet are touching the ground, then she is in control of the machine. There are a lot of unfortunate underpowered riding women (and men) out there who still think they must flat-foot a motorcycle in order to ride it.
I used to flat-foot the Vmax, then I put on the Corbin. Now I can't flat-foot it but I can certainly control it as well as ever, and I sure ain't going back to the stock seat.
What does SHE say???