I have had alot of customers ask me this same question and I always recommend the 280 AI for several reasons.
First off, bullets
A 160 gr 7mm bullet will penetrate at least as deeply as any 180 gr 30 cal bullet and in most cases the 280 AI will drive a 160 gr bullet to higher velocites then any 30-06 can drive a 180 gr bullet.
Also, the BC for the 7mm bullet is generally higher as well then its 30 cal brother.
Because the bullet is lighter, felt recoil will be less then the '06 as well.
The 280 AI has plenty of power for taking big game at extended range, at least as far as the '06 does. In this catagory, they are basically the same in performance but ballistically the 280 has the advantage.
If you want lighter bullets, the 140s will do in the 280 what the 165 will do in the 30 cal, again with less recoil and higher velocity and at least equal BC in many cases.
If you want a heavy bullet option. The 175 gr 7mm bullet will do anything the 200 gr 30 cal will do and in most cases out penetrate it while again doing so with less recoil.
Yes the '06 will have a longer barrel life but not dramatically so if you take care of the 280s barrel and not over heat it I would not be to concerned about this as they both offer good barrel life.
Just my opinion that the 280 AI is a much better long range round then the '06.
Kirby Allen(50)