I would go with the 30.06 over the 7mm mag simply because the 7mm is a mag.
No need to take the recoil with such closely matched calibres.
Now if you ALREADY had a 30.06 or even a ,308 then I would go with the 7mm mag because......well, you need one if you don't have one !! right?
Others have offered up a sighting of roughly 2 inches high at 100 yards as a good sighting scheme. In my own experience I have come to favor a sighting of 3.5 inches high at 100 yards. This allows for the individual to hold dead-on (directly in the middle of the top and bottom) the animal out to roughly 350 yards.
Magnum calibers such as the 7mm Remington and 300 Winchester will extend this slightly. At 400 yards I hold directly on the backbone of the animal. The drop at this range allows the...