I would also have to go with the shot gun they are alot more versatile ,they are cheap, ammo is cheap ,you can hunt just about anything with them ,a small child could not manipulate the action near as easy as a pistol,pistols can be diiicult to shoot accurately,not a problem with a shotgun,go with a pump action remington or mossberg in 12 ga.,women can shoot these things easily,i would suggest something along the lines of poly-shok ammo for home defense 100% energy dump into the target nothing coming out and lets not forget you hear a bump in the night ,they hear that slide rack one time there will most likely be no confrontation as said intruder will be looking to get out faster than intruder came in I promise you. If you want a pistol get a revolver .38 or bigger
Not looking to bust on you, man, but there are a few things you said that I have to disagree with.
#1: Shotgun ammo is not cheap. HD ammo, anyways. If you have a cheap source for 12ga, please shoot me a PM, I'd love to stock up on some more.
#2: It's been my experience that you do need a modicum of accuracy with a shotgun, even with something that has a nice spread, like say #4 or #6 shot. If you're talking about #00 shot, at close ranges like home distances, you'd be surprised how small the pattern can be. Not saying you need a fancy sight on it or anything, but it's not exactly a "point in the general direction" kind of weapon, like everyone makes out.
#3: Not many women would agree that a 12ga is "easy" to shoot. My wife hates it. Hell, even I'm not a big fan of going to the range and blowing off 50 rounds with my Mossy. And I'm a pretty big guy. Low-recoil tactical rounds help, and a Knoxx Spec-Ops recoil-absorbing stock helps even more. But I bet if you took any woman to the range, had her shoot a 12 and a 20, then asked her which she liked better (and looked to see which she shot better), the 20 ga would win 99.5% of the time.
#4: In a home defense situation, or any violent confrontation involving guns, really, you should never count on the fact that a racking slide is gonna scare off the bad guys. Some people may not even hear it from behind a closed door. Some people are just crazy. Some think that you aren't determined enough to follow through on your threat. If you want a second opinion on this, I suggest posting this thought over on Prac-Tac. You will ignite a firestorm of debate (again).
#5) Punctuation is your friend.
To the OP,
If you want my recommendation, get a nice 20 ga. Pump works fine, but it has moving parts, just one more thing that can go wrong in the heat of the action. Check out a 20ga side by side coach gun. Small and maneuverable, they work great as HD pieces. And hopefully you won't have to unload multiple rounds into your assailant to end the conflict. If you're worried about firepower, maybe you do want an 8-shot magazine, I don't know. Also, SxS shotguns aren't nearly as vilified in the courts as that scary tactical 12 ga. May be a consideration, maybe not. Just something to think about. FWIW, laser sights are nice, but I'll take a good flashlight/weapon light any old time.