My wife carries a P3AT as well. As far as .380's go, you have to be careful, as most operate as a "blowback" pistol, using nothing but the stiff recoil spring to hold the gun shut. These can be a bear to rack the slide on. The Keltec uses a modified Browning recoil system, and I think it recoils lighter than a PPK or Bersa, shooting them side-by-side.
The other gun you might like to have her try would be a Kahr 9mm like the K9 (steel frame) or the P9 (polymer framed). I have one of each, (well the P9 is a Covert model, with a truncated grip) and they are easy to shoot, chambered in a serious caliber, and I've found them to be more accurate than ANY sub-compacthasa right to be.
But, as has been said above, take her to a range that will rent guns, and spend some money on 3 to 5 boxes of different calibers, and start shooting the guns that match. Most women that I have instructed prefered the .380, .38 Special, 9mm or .45 ACP. The .40's and .357 Mag's and Sigs tend to be "snappier" than most women will commit to fire more than a couple of rounds out of.
I thought my wife would prefer a smaller revolver in .38 Special, (or a .357 mag one, shooting .38's in it), and I was about to get a Smith or Ruger for her. I'm glad I talked it over with her and took her to the range first, because she ended up NOT liking revolvers at all. She had no problem understanding the functioning of an auto and put it into practice with very little instruction. I don't have any revolvers in the house, and she can shoot and reload/operate every single auto that I have without a problem.