For the all-around utility rifle, I would have said 308 or 7mm-08 if you didn't already have the .30-30. But since you've got that middle ground covered, I'd go for the .30-'06 definitely, or possibly .300 WinMag, which as mentioned should be better for big bears or moose if you can afford to get up north.
BTW, I've been thinking about cartridges a little lately, and consider this speculation about the .280 Rem aka 7mm rem expr (if I'm way off, it's because this is armchair quarterbacking - I've never done a lot of hunting): seems to me this is about the perfect all-around north american hunting round IFF you are NOT hunting the alaskan bears or moose. IINM, It's just between .270 and .30-'06, with the same powder capacity, so it seems a perfect compromise betwteen these two colossally famous cartridges. It has the selection of 7mm bullets, second only to .308 bullets, and much more than .277. It comes within 200-300 fps of the 7mm rem mag, which is enormously popular now, with less shoulder punishment. A 175 gr 7mm bullet has an excellent BC for long-range shooting, is amply adequate for elk down, and can be pushed pretty fast. It can take lighter bullets like 115-130 gr if you shoot varmints with much better BCs than .308 bullets in those weights, so it's a great varminter as well. Only drawback is you can't go 200 or 220. Please agree or flame away.
Personally, I've noticed several experienced african hunters who write that they take much or all of the game with a .338 Win Mag, and have no need for the .416s or .458s or express rifles.
[This message has been edited by Futo Inu (edited November 01, 1999).]