This is basically the question that I asked myself when I bought my rifle years ago as a starving college student. I went with the 30/06 as it gives many, many reloading options and you can buy ammo anywhere.
Over twenty years later, I'd only add this:
1.) A 300 win mag, as was said, might be better than a 30-06 if you're in a brown bear world. I'm not, and probably never will be. I could probably make the 30-06 do with a good handload, maybe a 220 grain bullet if I ever got the chance.
2.) My choice of a Savage 110/111 is still seeming to me the best choice of all the makes. Besides being one of the few makers that produce affordable left-handed guns for people like me, 110s offer the advantage of being easily rebarreled. You can get a 35 Whelan barrel and a gunsmith could put it on with his eyes closed. It would be like a mechanic doing a brake job in terms of difficulty, I'm guessing total cost of $300 or even less, and you have a real bear cartridge certainly useable for deer.