I'm going to second the nomination of the Ruger SP101 .357 magnum. I think it fits your stated needs pretty well, for anything except an enraged, charging Grizzly. Revolvers are, generally, a little less complicated and a little easier to learn to use than semi-autos. And, the SP101 is a nice, compact, reasonably lightweight, reliable, easy to use and care for firearm. A S&W 66 or 686 would be nice also, but the SP101 is a bit smaller and more easily concealed, since it's a 5 shot, rather than a 6.