I haven't handled an LC9. I did have an SR9C and it was an excellent pistol.
Your best bet (as a married man
) is to have your wife handle as many handguns as possible. She'll definitely figure out which ones feel best. Then try and find a range that rents guns and have her shoot them or guns that are as close as possible.
Remind her that smaller guns recoil more and while they are easier to carry, they can be a pain to shoot. If she doesn't enjoy shooting it, she won't practice and she needs to practice.