Boy Nitrox, that would certainly be a very VERY good cartidge, but I would just have to take a 30.06. I suppose that isn't a very imaginative choice, and I can already hear people lining up to say that it is underpowered for the big stuff, but to me it would simply be the best for the huge range of game sizes. And I do not share the opinion at all that it is underpowered for the larger animals. Now, that would be if it were srictly plains game. In your question, I am not sure if you want us to also take into consideration the possibility of bumping into something dangerous while we are hunting our plains game, but if I had to take that into account, then I would go with you and the 8 Rem Mag. Not quite as suitable for the smaller game, not quite as pleasant to shoot, but some extra muscle for the beasties.