I think you are on the right track. SP101, one of the Ruger Six models or a K frame, 3" barrel+. Great first guns. I've found that most people (that want to) could work up to midrange 357 loads in an medium frame 357 quickly. To my way of thinking, better to have the capability and not use it.
The best thing to do would be to let her try various revolvers. Some ranges have rental guns, but that isn't available to everyone. Lots of shooters are willing to let you try their guns. Where do you live?
David