Some good long range cartridges for deer "on up" would include the 280Remington, 30-06, and 7mm Remington Mag. IMO, the .30cal. mags don't offer enough over the old '06 to make 'em worthwhile. If more power is wanted or needed, then move on up to the 338Win.Mag.
BTW, I completely agree with your assesment of the 243Win. - minimal for deer, and too small for anything larger.
As noted, a good bolt action rifle would be your best choice as opposed to a semi-auto. The Winchester Featherweight is an excellent choice. You might also want to look into the Remington 700 CDL.
Good luck.
ps: The Featherweight is also available now in stainless with a walnut stock. Good lookin' rifle.
Link:
http://www.winchesterguns.com/prodinfo/catalog/detail.asp?cat_id=535&type_id=966&cat=001C