HUNTING OR PROTECTION?
There's a big difference. For protection, you need something you can bring up, aim and fire *very* fast, and that can smash through the business end of a bear at 30 yards or less. Most people simply cannot bring a scoped bolt action hunting rifle into play that quickly. An iron-sighted lever action such as the 1895G with powerhouse .45/70's, or a slug gun would be good choices. Or simply go unarmed and keep your wits about you. There's something to be said for that choice, frankly, esp. if you're just hiking around established trails. Listen, smell, and watch for sign and you'll be fine. Where are you going? The bears can be very different from region to region.
For hunting, you're going to be shooting at the critical spots on the broadside, so you could do with less bone-bashing power, but will probably want something with a much flatter trajectory and longer range. The old .30'06 is still hard to beat, as are the other suggestions here. If you know where to aim, you could even get away with a .30-30. Hell, I was just reading about how members of the Karluk expedition before WWI dropped monster polar bears with old Winchester '94's (though I'm not going to try it).