As you mentioned Colorado, I recommend Over The Hill Outfitters in Durango, southwest Colo.
I have hunted with this outfit three times and found them to be top rate in everything. Hunting area, camp setup and equipment, horses, tents, food, and guides. Lots of elk in that area, too.
Were I to go back to Colorado for elk, I'd book with them.
http://overthehilloutfitters.com/EDIT: If I were you I'd take the .30-06.
L.W.
