.270 is a solid, all around caliber to do about anything with short of big game. Before I had my house robbed in Sept 08, I had my Remington 700 in 7 Mag for most of my hunting but I had a .30-06 in an old school Remington 740 semi auto with a short barrel. Awesome gun, to be honest. I drilled an 11 point offhand at 120ish yds with it. the point was having the long cannon for set shots from stands and the much more portable and flexibly 30-06 for hogs or stalk/rattle hunting was a good set up for me.
As far as calibers go.../shrug. Depends on what you want to do. Do you want a gun you can take on big game hunts if you ever have a chance? Do you want something that just shoots straight and clean, not necassarily a cannon? .25-06 is pretty slick for that, IMO.