I was always annoyed by this since the first civ game, I just couldn't fathom a lil phalanx sinking my great battleship. I dunno maybe they lodged a rock in its nuclear reactor or something.
So anyways, I also went into the editor and did the following:
I divided the units into rough eras. The warriors were on an era all of their own, then the next up: spearmen, chariots were giving a point boost in def and atk respectively.
Next on, were swordmen and horsemen. These I also increased one point each in attack and defense, if I'm not mistaken.
What this does is make it advantageous to upgrade units and it gives them a bit of an edge over the much cheaper and less impressive warrior unit.
The next step was taking into account the spearman and swordman as the standard combat units I started basing all my calculations for the next units on their stats. Basically, for every new warfare era I multiplied the previous era's stats by 2. So a pikeman has 6 defense instead of 3. Likewise the next defensive unit in the chain has 12 defense, and so forth, until the mech inf has some 40 something defense (don't have the editor open at the moment so I can't check the stats atm) BUT, I also increase the attack and defense of other units in that same era commesurately.
What this does is very simple it makes the odds between units in the same era roughly the same. So, a swordman's chances versus a spearman are about the same as a knight's chances versus a pikeman. (roughly) But a swordman's chances versus a pikeman are severely dimished due to the x2 era multiplier, almost halving it's chance of succeding. This trend continues until the lowest units have about a .168% chance of killing a tank or other modern unit. Which is well within acceptable limits.
The one exception to this rule I made was with infantry and tanks. I consider them as half step, as they're quickly followed by the modern armor and mech inf. So the mech inf and modern armor are only 50% stronger than these units, instead of the usual 100% increase.
Simple put you're creating a warfare pyramid, where units fighting within the same level have fair odds versus eachother, but units attack from different levels suffer big penalties.
Hope this might give people some ideas or suggestions if they decide to tinker with the units. It's fairly straightforward and easy to do, you just multiply the units given by your era multiplier and put those new numbers into the editor