Lots of good info here already, I have a 2.5-8 matte Leupold on my 375, it guides the 270 gr TSX's at 2780 fps to a 200 yard zero, it sits in steel Talley QD rings, the barrel iron sights are dead on at 50 yards with the 300 gr BBW #13 solids, BTW, the solids zeroed at 50 are on at 25 yards too, I can't tell/shoot/see any differences between the two yardages.
This is another combo that would work for all game anyone would point a 375 H&H mag at anywhere in the world.
The 375 H&H makes a lot of sense. Even for plains game animals. If the distance is going to be far, I don't see any harm in running a 2.5-8x36, 3-9x40, 2.5-10x40, or even a 3.5-10x44. I've tried the M8 4x, 1.5-5 vx3 and the Zeiss conquest 3.5-10x44 on my 375 H&H and have to say I prefer the power range of the 3.5-10x44 more than the others. I see the 375 as a powerful cartridge that has medium to long range capabilities as well as short range capabilities, thus making the higher power scopes very useable in the field. However, this is coming from a 3-9x40 lover. Started out on one and will probably continue using them for as long as I can... Of course YMMV...
