Traditional response to handle most things that could bite ya, for me, Win 94 Trapper in .45Colt along with Ruger SBH or Vaquero. .44 Mag or Spl is fine as well for most, as would be the .357 family.
Beretta, Hi Point, etc... sure, why not? With any of the choices, just know your limitations and the round/firearms of choice. I don't personally know about knockdown power, more about making holes in things where I want them, and I do believe in the "Bigger the Hole the Better" theory in this regard, myself. Up to a point.
Could also make do 99% of the time with a .22 tho, truth be told. Unless you rile up a moose or two. Most bears will scamper away, (spring time avoid/watch out for cubs w/ moms nearby), cats are cats. Know your bear etiquette when out and about (food storage when camping out, etc).
While I have yet to meet or run into a bad person or group thereof when out and about in the CO hills, I suppose they are out there, but most of the rest of the people I've ever encountered along any trails will gladly give you the shirt off their back if you need it. Except maybe for their guns. (those that do carry are just as polite as those who do not in my experience)
Beautiful country. When hiking there the past 10 years or so, I typically make do with a S&W 442 and it has never seen the light of day for reason of defense. Yet.
Hunting season is different.