Thanks for the posts Guys,
In the conversations the .243 won out for the same reasons that y'all mentioned, mostly ammo availability, He is not a reloader, and I am, thus the perfered difference.
I also mentioned the .257 Roberts, (I have a real nice Remington 700 classic) and I love the caliber, also the 6mm Remington, for the long action (sporterized mauser) aspect...
But, if it were me, the appeal of a "nostalgic classic" and a little different than the ordinary caliber would have my vote for a first gun..
A couple of new-comers, the .260 rem and the 7mm-08, especially in a youth model, were discussed as well, but the .243 seem to be the winner of the "first rifle" argument.