Even though it's late for the thread, I'll throw my $.02 cents.

If he can handle a 30-06, I'd go with that because because he's soon to be off on his own or off to college. He'll have a rifle he can use on virtually anywhere on anything until he's able to start buying guns on his own.

Another possibility is the .308--less expensive ammo that's lets him plink without blowing the bank.