I agree that .243 is an excellent choice. And is exactly what you want if the largest game you are after is deer.
A step up in power among the "commonly available" calibers is the 7mm-08. This is still a light recoiling cartridge, but is suitable for anything in the lower 48 states. I would have no hesitation to use it on elk, black bear, deer, cougar and even moose. I would want more gun for brown (grizzly) bear, and polar bear.
If I am buying a weapon, I like to get one in a caliber that can be purchased even in small towns, and where a few boxes of ammo doesn't break the bank.