Gun Control & RKBA

First, a shotgun is far and away the best defense weapon. The sound of a pump shotgun being racked is probably burned into the psyche of every American male over the age of 5 in this country. Plus, they're damn near idiot-proof - simple to operate, and reliable. However, if you don't want a shotgun, then:

Between Glock and Springfield, I recommend either a Springfield XD 9mm with a 4 or 5 inch barrel (Springfields have an additional grip safety that the Glock doesn't, that will help to protect against accidental discharges), or a revolver like the Ruger GP-100 in .357 magnum that you can load with .38 special rounds. If you get a semi auto, remember that you either have to leave the gun in the drawer with a round in the chamber (which means the pistol is sitting in your drawer needing just a hand to grip it and pull the trigger - a bad idea if you have small persons running around the house), or when the shit hits the fan, you'll need to remember to chamber a round before it's anything more than a paperweight.

Another possibility is a CZ-75B, or a clone of said CZ like Tristar, Jericho, Magnum Research, EAA, or SAR. CZ-style firearms are well-designed and reliable semi-autos with plenty of capacity. The only issue you could have is that the slide profile is pretty low, and it might be difficult to rack the slide back. I have an EAA and an SAR in 9mm, and sometimes my old hands don't like the low slides. Other than that, they're both fine weapons. As a matter of fact, the SAR is sitting in my nightstand as we speak.

The best answer is to find a shooting range or gun shop in the area that will let you rent guns to try them out, and see what feels best to you. Hell, you may decide that the best answer is a 1911-style .45...you never know. After buying it, take it out and put at least a full box of ammunition downrange per user, so that you know what it feels like. After that, it's a good idea, if possible, to get out at least once a month to stay in practice and remain familiar with operating your firearm.

I hope this is of some help to you.

On edit - second the gun safe with a bio-metric lock. Safer for all concerned.

Also, I have a Springfield XD .40 with a 5-inch barrel, and a Ruger GP-100 .357 magnum with a 6-inch barrel. I like the Springfield ergonomics better than Glock, but that is personal preference.

Finally, don't count out other calibers such as .380. With the right ammunition, a .380 can be pretty potent, and there are a lot of good manufacturers making them at a reasonable price. Bersa, EAA, Chiappa, Walther and KEl-Tec come immediately to mind.

Find one that feels right to the both of you, shoot it first if you can, and once it's yours, practice!