In Oregon we have the big cats and Black Bear. I'm with 4x4 and the cougars worry me more than the bear given the tendancies of each. In most cases the black bear really isn't interested in people unless their is something wrong with it or a mother defending her cubs kind of thing. Cats tend to take a much more practical view in that any 2 or 4 legged meat sack is on the menu providing they think they can take it without getting took themselves. Deer venison might be prefered but I'll do in a pinch. Just my non-scientific opinion. A 357 mag is a good practical choice and likely the 44 mag represents the sweet spot and the upper end of what most of us mere mortals can actually proficiently handle. Grizzlies in Alaska the size of Rhino's? I'd like some air support please or maybe a Humvee with a mounted 50 cal and gunner following me every where I go. Better yet I'll just ride in the humvee with the crew. Safety first.
The only thing I can really add to the good advice already given is don't discount the value of a good sheath knife. The idea of hunting rifles, 12 GA and powerful magnums is taking for granted you/we have the time to use it. In the case of a charging animal you may have time for one good shot maybe two to get the job done. What if you miss? What if you just wing it? What if you don't have the time? What if the first time you see the animal is when it already has already knocked you to the ground and is gnawing on the back of your head? With a bear, any bear, maybe not much beyond going fetal and screaming for momma. Not very dignified or effective but always an option. In my case the high pitched little girl screams and the stink coming from my poop filled trousers might confuse the poor creature long enough for me to scurry away to safety. With regards to a big cat I think a long sharp blade represents a good last resort weapon when your on your back fighting for your life and at that point I would think it is infinately more practical than trying to employ a fire arm that I might accidentally shoot myself with in such close quarters. For bears a knife may not be ideal but is more effective than harsh words and dirty looks. By all means carry a side arm especially as a hiker who doesn't have the benefit of carrying a hunting rifle but add a good sheath knife to your belt for good measure. Complete the kit so to speak. Just a thought.