On the .22 wmr, make sure she tries one at an indoor range before buying her one. Maybe it's just me, but those things are ear piercing load even with muffs. Because of that, I decided years ago that I wasn't interested.
When I was shopping for a snub for the wife way back when, the shop I loved also catered to the needs of the local PD. I was looking at Det Specials, model 36s and the cheaper Rossi 3". They told me that the police that had trouble qualifying with snubs would use the 3" model 36s. So that is what I bought her and I enjoyed it as much or more then she did. I even used it one time at a bowling pin match and was amazed how well it handled pins rapidly. I also like how the extra inch seems to stabilize better iwb and helps keep the butt in tighter. They are just "comfortable" guns to shoot compared to the 2" version. Now, when I was looking at the new Colt Cobra and Kimber, I was able to compare 2" and 3" in both models. I was very surprised that in my hands, the 2" Cobra balanced and pointed the best for me, in the store.
The issue for the op seems to be which is best for AIWB. I can't help you there since I don't care for that carry method but like you, the few times I tried it with a 3" I wasn't comfortable. I have an older CA 3" Bulldog .44 special that I do often pocket carry. I simply check the new pants, making sure they have deeper pockets. It puts the butt just below the pocket opening which makes for an easy draw with no searching in a deep pocket for the grip on a smaller, shorter 2". The 19 ounces also seems to be the cut-off weight for me when it comes to sagging the pockets like some all steel snubs do at 22-23 ounces.