I am a 9mm fan and carry 9mm when I carry IWB. I also sold away my pocket .380 because I prefer the .38 for a self-defense round (pocket j-frame). If you are comfortable with .380 as a defense round (many are and I don't argue with them) there are many nice choices available. I went to the range with a buddy last Saturday and shot his Walther PPK. REALLY nice gun and I was surprised with how accurately we were both shooting it. It's probably the only .380 I would own right now due to "cool-factor" alone. If your wife has small hands it would be a nice choice.

If you're looking at something bigger in size and weight, like a Sig P230/232, Beretta Cheetah or similar, then I think it makes sense to at least consider a 9mm because of the availability of 9mm guns in a similar size and weight. Consider how she will carry and how much she will be shooting it. The reason I carry the 9mm's that I now carry is because I shoot them all the time when I go to the range, vs. not really shooting my carry .45 that much. A POCKET size/weight .380 like the new Taurus or the Kel-Tec, Ruger or other "mini"guns, is sometimes not much fun to shoot. Sometimes its a lot of recoil for small or weak hands. Some of the more carry-able 9mm's are not that much bigger/heavier to carry, but are much more enjoyable at the range, and that's a good thing.

If she can carry something as big as a S+W 39series, "full-size" Kahr, Sig 225/P6, CZ compact or something of similar size and weight, I think that's the best compromise because they are, at the same time, big and heavy enough to enjoy shooting at the range while being small/light enough for comfortable carry.

Good luck and have fun shopping with her!