Scorched earth was awesome... although the guidance systems killed it a little, it was much more satisyfing to land your heavy napalm just thru angle and power.
For the Civ IV players out there, try the Fall from Heaven 2 user mod. That was my staple for months before finding Dom3. Still the same combat system, but it is a very rich fantasy setting, huge differentiation between civs and religions, plus lots of magic
All while maintaing pretty decent balance. It is supported amazingly well by the development team.