If you are talking of an Uberdistancesmashemboomer, and cost is not part of the equations but a less common caliber is, why not go for a .308 Norma Mag or a .30-338 or even one of the H&H's?
Personally, my choice would probably be the 7mmSTW for those times when you absolutely, positively, without a doubt needed to reach out and touch something.
Now, if you are wanting some real knockdown power out at long range, check out the custom built 700 a friend made.
http://www.youtube.com/watch?v=kFYXTH7Gdhk