Yeah, I'm w/Wiley--thanks for forever making me need male-enhancement products SI. Actually a shotgun can be LESS-destructive to an interior than a pistol--that's the nice thing about them: they're versatile.
I believe Guns & Ammo (or it might've been "Gun Tests" magazine) ages ago did a comparison, and found that birdshot, although fired w/in 10' would go through a bad guy without patterning at all (in other words: one giant lump o' lead), #7.5 or 8 shot would be stopped by only one thickness of dry-wall, thereby saving your kids or neighbors (if you live in an apt. complex or a duplex like so many in NOLA do), while even a JHP round from a .38 would go through a couple of interior walls. Buckshot, on the other hand, also keeps right on moving, and slugs... I also like the idea of a 20 ga., since being a sissy, I'm tired of the 12 ga. doing more harm to my rotator-cuff than any damage I'll probably do to a bad guy, although I've owned (and reluctantly shot) many 12 ga. shotguns. Basically, if you think "girl-y gun for the recoil-sensitive" you think me: I LOVED the 7x30 Waters when they made it for lever-actions. But I'm a weirdo.
Lots of gun writers, including Massad Ayoub, who I've always thought got some good points in the "it sounds like common-sense" dept., advocate a shotgun as a home-defense weapon w/a pistol as the back-up, rather than vice-versa. I'm not saying anyone's choices are poor: after all mine is an old S&W M&P--no NOT the modern automatic, a REAL S&W M&P, as in made in 1948. You have to fire one to understand why ever-damn-cop in America carried them for 70 years--that trigger-pull; y'know, back when Detroit still cared...
I'm just suggesting it as an option, and you could do worse than load that Thumper w/2 rounds of #8 for starters. I'll give you the buck or slugs after that--if you haven't got the bad guy after two round of #8 inside, you're gonna need the big stuff.