As many have noted, the fighting in the MA frequently revolves around only a few bases, with much of the arena being empty most the time. It is possible to spread out the fights in the MA and you don't even need a bigger terrain to do it (although in the case of AH you would probably need some programming work)
Here's how:
Zone limits. Each base is in a "zone". If that zone is FULL (too many people in the area) then this base cannot launch any more planes. This would make the fighting spread out. I don't know whether AH already has a system such as this, but if it does than the limits are too high.
AH would need some sort of active zone system due to the amount of base capturing--as a country lost bases, its zone limits for remaining bases would need to increase. Otherwise, pilots for a country that's "in the bucket" might not be able to find a field to take off from.
I would make GV's and field guns not count towards a ZONE population limit either.
Comments?
J_A_B