Although I own and have shot many a critter with a 300 wm I generally tend to recommend away from magnums. They're sexy and all that, but not necessary for most North American game. If you know what you're doing with the venerable aught 6 or 308 you'll do great. My father-in-law grew up in Fairbanks and he talks about frequently shooting Alaska Moose with a .270 and thinking nothing of it.

The bigger end of Remington and Winchester families are tested and true and ammo is diverse, less expensive than magnums, and you can get it anywhere.