I really think if I was going to look for a big bear protection weapon I would look for a long gun. Probably a Lever in a cal 35 or larger.
As for me I can shoot a rifle better than a pistol (I bet this is true of about 95% of folks)and once I start getting to the kind of pistol I would want to aim at a 800 LB+ bear I might as well sling a Marlin guide gun.
Quick picks would be a Guide gun in 45/70 or 450, BLR in 358. or even an 94AE in 356 or 375.
I know that lots of people reccomend a shotgun and I am sure it would work. However, once nice thing about a rifle is you can load it down and do some serious practice. if you blast tin cans for a couple of hundred rounds a yearyou be much more likely to be on target when you need to be on a bear.
For the Lower 48 I would be more worried about two legged preditors and a autoloading handgun in 40, 10mm or 45 would be my choice.
My woods carry? a 4 5/8 blackhawk in 45 colt 250g cast bullet at 1000fps. Why?... because I like it