I really like Traveler's suggestion of a road system that means something, and functional, destroyable bridges that span rivers.
Seemed to me that too many ground battles were static engagements that lasted as long as vehicles were available from the involved V-bases. As soon as one side knocked out the VHs, the battle ended and moved somewhere else on the map.
What about adding a whole new target to the maps - capturable villages? With real, useable roads and bridges connecting towns, and capturable villages along these roads that could serve as resupply depots for the attacking columns? We could see ground advances into enemy territory along these routes. With a new vehicle like the Deuce-and-a-half that could carry 10 troops, captured villages could provide repair and refit to attacking forces to allow for sustained pushes into enemy territory. Bridges along the routes would serve as natural interdiction targets for defending air units, as would the columns of advancing units moving long the road...