I will second what AJ stated.
The only thing he and I will dissagree on here is the calibers.
Everybody has their favoraites and for different reasons. I like 308's simply because I have always got along with them extremely well. With the vast variety of bullets available, long barrel life, ease of tuning, they just make sense for a practice round and can double up as a hunting rifle as well.
So can the 708. Since you will be having a 7STW on the shelf and lots of 7mm bullets hanging around, the 708 may be the ticket for you.
If you want to "play" with another caliber, then the 308 is an outstanding choice. You wont go wrong with either.
I will also second AJ about the hornaday spire points. I have had awesome accuracy in my 243, 308, 300 RUM, and my cousins 7mm Rem mag. Much cheaper too.