As a former guide and longtime resident/hunter of the Rocky Mountains, I think way too much is made of which caliber is the best elk cartridge.
My first gun of choice is the one I have the most faith in. The one I am the most cionfident in. That is what is supremely important. Sure, a large magnum will knock 'em down at farther distances, but how good a hunter are you to not be able to get "within ethical range". And how much flinch can you subdue when it comes down to the rubber hitting the road? Besides, I tend to think that the large guns tend to give a hunter false hope.
So use the rifle you are most comfortable with and don't fall prey to "how big is your gun?" Capice?
Naturally, you don't want to go after a rhino with a fly swatter either. The biggest gun you can trust and comfortably shoot, that's the gun you take. Also, Launch a bullet that penetrates bone and flesh well and then opens up to do damage.

Then you practice, practice, practice!!!!