Neither one of us could work the slide worth a damn on the M&P 9mm
It's a larger gun than the XDS, but the slide on the HK VP9 is great. They make it with a little set of gripping "wings" on the back of the slide that make it incredibly easy to rack. Almost bought it except I'm not a fan of the Euro-style paddle releases for magazines. But a great gun with fantastic ergonomics. Almost aims itself.
Still considering a smaller, single stack gun for carry, though. Can't quite make up my mind. My wife hasn't shot pistols very much, and even the 9 kicked a bit much for her. I'm thinking of starting her off with a .22, like a Ruger DR-22, M&P 22, or maybe even the PPK/S. Ammo is cheap, very fun to shoot, and she's a lot more likely to get good with that than with a gun she doesn't actually enjoy shooting.