Nothing better than a good wheel gun. I love S&W, you can find then used for less. Tarus us pretty good too. I would say a 4in 357mag would be best. You can start out with lite 38 special loads. Work you way up to 38+P's. Which would not be a bad place to stop for the wife. Or move onto 357mags. There are even lite loads for them. 110grn med. vol. loads. The best 38+p hit with about 278 foot pounds. A full house 357mag hit at about 578 fp. The 110grn runs at about 410 fp's. More pop, but less punch. The Smith K frame is a good size. A lot of folks like semi auto's. And they are good. But you say you and your wife are starting out. A wheel gun is the easyest to learn to use. And seldom jam. If it does not go bang, most times pull the trigger again and it will work. If a semi jams, its not as easy to clear. I have many of both types of hand guns. But my travel and house gun is a six shooter. A Smith mod 66 with a 4in bbl. Both my kids and my wife know how to make it work. With all that said, I think the best house gun is a pump shotgun. You can pick up a 20ga and with a little work every one in the house could hit a bad guy. With a shotgun, you do not have to be exact, sometimes, close is good enough. As the old saying goes. A shotgun speaks louder to a croud. I hope this helps a little and I hope you never need to use it.