I gotta agree with Mike - the handgun is (I think) the most verssatile, USABLE piece when in the house. Your 870 may get lodged crossways in a hallway or doorway. And maybe you might need one hand to assist wifey, move Junior, or restrain Brutus until the crucial moment.
Any longgun, including the AR-15, unless it is an M-4shorty, same; likewise the Mini-14. and as good as they are in outdoors notwithstanding , it seems to me, my ability to use or control may be compromised with a long gun.
I might opt for my .30cal. GI M-1Carbine loaded w/ 110gr JSP, but same thing - it might be a bit unweildy in a hallway or close-quarters issue, .
I think now my most likely respons to something that went "Bump !" in the night would be with a 3-cell Maglight carried in the weak hand in the over-the-shoulder position (you know, it makes an awfully effective CLUB, that way) and the Kel-Tec P-11 strong-hand, close to the body to give a higher assurqance of retention if it got to close-quarters. Yes, a little Kel-Tec, and not the huge 1911-A1, for that same (retention) reason. A big guy could maybe get a grip on the front end of the .45, but with the little 9mm, I have a higher likelihood of maintaining posession and control. Close in, from the hip.
And NO racking of the slide for me. I want to hold for myself the element of surprise. My plan is to place my family in a secure and safe position, armed - then to cover the approach - I don't go hunting any more. Stealth.
I've only had to roll out twice in my lifetime, and once was in skivvies and barehanded. Maintaining the element of surprise made my tactic successful and I took the guy down. (But I had the adrenaline-rush of a lifetime, for an hour afterward).
I like this thread you have started here - proper prior preparation insists on considering at least a few of the most likely scenarions one could become involved in and thinking them through, well in advance. Maybe practicing that kind of scheme at the range sometime, to see just how you might work it or improve upon it.
Flash