The Yamaha is probably a good idea. A friend of mine did exactly that (same bike and everything) when he wanted to get back into riding. Once he established it as a good fit for his business (he travels to customer sites all day), then he bought a new 250 (because it’s all city traffic).
Another option might be a third generation Magna. It’s what I started on, and what I still ride. She’ll probably drop it at least once-I certainly did-trying to do something at low speed she’s not ready for. But they can be had for about $3k, they have very even response to the throttle, and they have the reliability you expect from a more recent metric bike. Also, the seat is low enough that even a short person can ride it. My daughter is diminutive of stature, and she can flat-foot two feet on my bike.
She won’t have trouble keeping up with you either, unless you really decide to open up the throttle. The Magna engine is plenty zippy in experienced hands.