.22 - Make mine a CZ-452 Lux
30-06 - M1 Garand
30-30 - Winchester 94 (or similar -- other calibers are fine here as well)
---------------------------
Those would form a nice base for a collection. You would be able to plink and hunt many, many critters in North America, and even have a classic military firearm.
If you want to branch out into other milsurps, great. If you want to get into EBRs, fine. If you want to thwack groundhogs at 400 yards, then get something with a big honking scope and super-flat trajectory.
I think that the above would certainly be a good start.