The 8mm-06 or 338-06 will give up little to the 338 Win Mag. Especially if you hand load for the 8mm-06.

The 375 H&H is, IMO, a lot more gun than anyone will ever need for North America. That's not to say that it isn't a good tool for the bigest of bears that this continent has to offer but it is certainly not necesary.

A very good "in between" cartridge that you are looking for would be the 350 Rem Mag. It should be right up your alley. It will drive a 200 grain bullet at almost 2800 fps and a 250 grain bullet at about 2500 fps. It is very suitable to any thing that this continent can throw at you. It makes an excelent elk on up cartridge. It is a belted short action cartridge and makes for a very potent big game rifle.

Ok...I think you guys are helping me make a case for 2 guns! (of course this will be the LAST 2 guns I will ever need...honest dear!)
Since my biggest/most potent now is with my 8mm/06 and/or the 30/06............. I guess I should have a .338 win mag AND a 375 H & H ....
I would think this would truly round out the cabinet (except for that lever gun in 45/70!)

The 350 Rem Mag would be another good choice. With the new rifles out for it now, it should get a new lease on life. It was and still is a great round suitable for all North American game. AND MORE.

340 Weatherby, that's a good idea. I'm guessing that it would give you something like a 200fps or more advantage over a 338 Mag and what, maybe 400fps over a338/06?? Does anyone know the fps on the 340? It would definately make the longer shots a little more manageable.

Thanks to all so far..........
After taking all the comments to pencil and paper...and comparing the lowest grain ball and highest grain ball listed in some of the loading data in my books and on the net....I've narrowed the search down to .338 Win Mag and the 35 Whelen........mostly b/c of the availability of ammo and components for both...I do reload, but would like to be able to grab some boxes off the shelf sometimes. When I logged agraph of the bullet weights being listed in the data, and compared the velocities for 338/06, 338 win mag, 340 weatherby, 375 H & H, 350 Rem, 8mm rem mag, and the 35 Whelen...........it showed me the versatility of the 338 and the Whelen from their bottom ends of 150 grain balls (Whelen) to the upper end 300 grain balls (338).
Thanks to all for you opinions and views...I think the 35 Whelen or 338 will serve me well as an "in between" my 8mm/06 and the next big dream purchase...the 375 H & H.
I can see that the 35 Whelen gives up a little in performance (velocity) to a few of the other rounds I considered at most bullet weights...but those few hundrend fps lost are easy to swallow when I see the wide range of performance this cartridge covers. I'm leaning towards the Whelen. (Besides, b/c I own a model 98 in 8mm/06, I could convert my Savage 30/06 to the 35 whelen with an Adams & Bennet barrel conversion from Midway)