The 7mm cals are a great choice for any of the hunting we have here in North America and they are probably the best choice when you take all factors into consideration. There are many other cals that will do the job very well like the .300 win mag, .300 RUM, .300wsm, 6.5x55, .264 win mag, .270 win ...
I shoot some pretty accurate rifles including, but not limited to, a .308 win, .300 win mag and a .338 Lapua. My experience has led me to believe that any of these calibres will work for long range but all have drawbacks. The .308 is limited in range to about 6-700 yards, the .338 Lapua is somewhat heavy and even with the muzzlebrake a heavy-hitter and the best fit I have for LR work would be the .300 win mag but the configuration I have is quite heavy and I don't like the muzzlebrake for hunting.
So, in true gun nut fashion, I decided I need another rifle. I ordered a 7wsm from PGWDTI here in Canada with an A5 stock, short action(their own), 24" Krieger barrel and removable muzzlebrake. I believe, for me, this will fit the bill for the best longrange rig I could design.
If I were to build on a long action I would probably go 7stw, the extra speed is nice to have but still very easy to reload for.
Enjoy your quest for the perfect calibre, it will take you a lifetime to find it!
Ivo