Take her to a gunshop and have her handle various guns to see what she likes.
I'd followed the thinking of a DA revolver but when I took my wife to the range to shoot her Tauras 605 the DA trigger pull was too stiff for her. So if you do go DA revolver, make sure it has an excellent and fairly light DA pull.
The flip side is some autos have a slide spring that is difficult for women to rack.
