Premium bullets have made better killers of standard calibers, like using an '06 on elk. Still, I am one those guys that, when measuring the balance, would rather err on the slightly heavier side. I consider elk big enough, tough enough and often found in places rugged enough that I like the idea of whatever little extra a bit more oomph could provide.
First, I think gmsemel is absolutely right that if you've got an '06 already the move up to the calibers you list really is a fairly small step. I mean, it's there, but if you want to step up I'd strongly recommend going ahead and getting a mid-bore. This could be a .338/06 or a .35 Whelen (.338 Fed?) on the "lower" end. By lower I mean you'd be dealing with less recoil and be giving up some velocity for longer shots if that's important to you.
IF you don't have recoil issues I'm a fan of the faster .33's like the .338 WM or what I have (and something that sounds as though you'd like) a Wby MKV .340. Insanely versatile cartridge. With it's favorite 210gr load it's as flat as my 7mag's favorite 150gr load or it can be loaded up to .275gr A-Frames for...whatever. The Winchester is really the same thing that just hasn't put in quite as much time at the gym buffing up.
