Personally, I'd love it if they calculated something's power by the number of units in that squadron. Heck, you should be able to build a certain type of warrior for however long or short you want, to get the results you want. Let me elaborate.
Say I want to make a small group of infantry. So, I build an infantry unit for two turns. As a result, I get an infantry set of, say, 1000 people. On the other hand, if I built up for twenty turns, I could have a set of 10000 people. And my power in battle would accordingly work out depending on the technology and size of the opposing side. If my 1000 Marines men go up against 7000 Grenadiers, it'll be a close battle, because while they have the numbers, I have the technology. Of course, the size of army built would correspond with the unit type; twenty turns of gunship building would not give me 10000 choppers, probably more like 100 or so. I won't make exact numbers here, though; it's the idea I'm talking about.
And, of course, the winning side of a fight between two armies will still end up with casualties based on the odds. My Infantry, even if they beat the huge number of Grenadiers, would lose quite a few men in the process. Likewise, the Grenadiers would not lose all of their troops, because it's very rare for an army to lose all of it's fighters in a whole war, let alone a single battle, though if it were a small number of fighters to a big one (Say it was an army of 70 grenadiers instead of 7000), it's possible that it would turn out that they all perish. It wouldn't be a huge remnant, but it would be something to, hopefully for the one commanding them, rebuild off of.
Also, in this system, I'd like to be able to group all of my units into one army, as in, if I want my riflemen, cavalry and grenadiers to join together and fight as one army, I should be able to. The bonuses would still be there, but of course, my rival would also be able to group against my units. So I could have an army of 10000 troops overall, consisting of the previously mentioned unit types, going and trying to sack a city all at once. Of course, the fortified units in the city will still hold up pretty well.
And adding to this system as well, I should be able to choose, when I'm attacked, to either fight with my unit, try to retreat away from the attacker (based on movement qualities of the army), or to surrender the fight, thus letting them take my army as POW's, which, if I manage to defeat this army who captured them later on, I would be able to recover some of. Like, if I surrendered with an army of 200 to an attacker, then later managed to defeat them, I could recover, maybe, fifty of them, all of it depending on how long they'e been POW's.
And to go completely away from that idea, an option to choose a smaller units of time passed as time would be cool. Maybe by the month or something. Why? Because I'm sick of wars taking seventy-five years, when we all know wars hardly ever go that long. I know it's possible, having played the American Revolution scenario, so I'd like that as an option.
Beyond that, I'm pretty content with what we have going in the series.