RE: Handgun caliner for wife?
The first time I took my girlfriend (all 4' 8"and 82 lbs. of her!) to the range, we started with a Buckmark .22lr. Then we went up to my Taurus tracker with .38's, & she did fine. I loaded a few .357's in there, & she still held her sight picture well, without flinching. Lastly, we stepped up to my Kimber 1911 in .45, and she'd take 2 steps back with each shot. STILL, she didn't flinch!
When we go to the range, she's still all about the Buckmark, and she's quite good with it, too. However, she took the .357 when we went hog hunting. We BOTH wanted her to have sufficient power for the task,& she was consistently able to bust clay pigeons on the 50 yard berm with that load.
So, my advice would be to introduce her to shooting (if she needs an introduction) with a .22, and to do most of her shooting with that. That will ensure she's good good fundamentals. Then, for home defense, I'd suggest she go with a .357 mag, .40 S&W, or .45. Anyone who's well trained in a smaller caliber can handle short stints at the range with these 3 calibers, and you'll be assured of serious stopping power should the need arise.
My $.02,
FC