Depends on the type of game you hunt most. If you mostly hunt deer, I would look at the 6.5 or 257 calibers.
If elk is what you hunt most, I would step up to the 338 cal. for longrange.
That being said, the 30cal that you have now will do anything you will need it to on game.
My choice for the 6.5cal would be a 6.5-06AI.
Standard dies are availible and good brass to. 26" barrel will get you 3200fps with 140gr bullets. Has #1500 energy at 800yards which will take out an elk.
Better barrel life than a 6.5 STW or 264 Win. You could load it down with 100gr bullets for deer.
My choice for longrange elk is a 338cal.
There are alot of great calibers in the 338's.
338 Norma 26" barrel
338 EDGE 28-30" barrel
338 Lapua AI 28-30" barrel
338-408 Chey-Tac