I think Fantasy Wars got this right. Really good TBS series, IMHO, for those that haven't tried it.
Anyways, in that series, when a unit attacks all the men in that unit run into the target square and fight it out for a couple seconds. Cavalry runs down infantry, spells throw guys about. It is a small thing, but it makes the battles feel more alive. Probably outside the current scope of Elemental, but it would be nice for the 2nd Expansion or a future sequel.