I would advise against the 10mm.
I don't mean to generalize, but females tend to have smaller hands. Small hands require small grips. Small grips mean small frame. Small frame 10mm's are a bear to shoot. That's a lot of power for a full size, let alone a smaller frame pistol.
Revolvers are usually female favorites because they have nice small, manageable grips. They're simple, reliable, and inexpensive. Can't go wrong. AND you can shoot both .357 Mag and .38SPL from a .357 Mag revolver. Nice.
If you want an autoloader, I'd go with .45ACP or .40S&W. The .40 is essentially the 10mm cartridge with a shorter casing---less felt recoil at the expense of less power (but still more than adequate for personal defense). And the .45...it's just a great round. It's a timeless classic that doesn't need an explanation. It puts big holes in things and isn't too powerful for the vast majority of shooters.
9mm is good if you're looking to send a lot of lead downrange. It's cheap, but .40 is a better performer, IMO. I like to use 9mm in my small carry pistols because I can get more bang for my buck with regard to magazine capacity. I make up for it with +P+ JHP ammunition.
The best advice? Go shooting! See what you like. If you go to a range and put your charm on, guys will be more than happy to let you shoot their firearms.