Zack,
Everything you said about the .308 Winchester is correct. It is a wonderful cartridge and will be the best of both worlds for you. In its regular factory loads, it has about 94% of the power of the .30-06, but with approximately 30% less free-recoil energy. If you want a more powerful load for elk, you just buy one of the factory Hi-Energy or Light Magnum loads, with a premium (Nosler or Barnes) 168 grain bullet, and you have the same power as a standard factory .30-06 and more than enough bullet to handle the job.
The .270 is a wonderful deer round. Yes, it can handle an elk, but is marginal for the purpose and leaves no room for any error. Given a perfect shot, yes it will dump one. But, stuff happens, shots can be pulled, wind can shift, game can flinch, range can be misjudged, and then that 150 grain bullet will wound the game.
No reason for your head to hurt. Go with the .308. And if not, then go with the .30-06.
Best,
Mannyrock