Since all you plan to hunt with it is varmints up to coyote and plinking, I'd strongly recommend a .223 Rem. The .223 is plenty "flat-shooting", can be extremely accurate (depending on the rifle), doesn't kick much at all so anyone can tolerate shooting it all day, and the ammo is very inexpensive. Black Hills makes great commercially remanufactured .223 Rem ammo that it very good ammo for little money.

If you are willing to spend a little money, I'd look at one of the AR-15 clones out there. There are many makers of AR's that make rifles that will outshoot all but the best bolt-action rifles, and being semi-autos, they make a great plinking/predator rifles. Look at Rock River Arms, DPMS, and Bushmaster. All make outstanding rifles. I watched a guy take a brand spanking new Rock River Arms varminter out of the shipping box, swab out the bore, load up a mag of Black Hills 55gr .223 and shoot an honest 1/2" 5 shot group at 100 yards after just a few sighters. It made me wonder why I was still stuck on bolt-action varmint rifles.

Mike