Having the best piece of ground isn't always the best strategy. Napoleon was very good at turning manuevers by making the "choicest" ground so heavily bombarded that it was suicide to keep it. Having some artillery and good missile units that I could place in a good position, I've discovered that I can make it very disadvantageous for an enemy unit to stay in place, no matter how elevated or fortified. This, however, depends on the map, but I've done it in both MTW and STW with fantastic results.

No matter how good a piece of ground is, it's not good enough to lose your army over.