I'll share with you a little piece on my ideas regarding my civilian/unit organization system, which I've been refining for a while. This has a strong base in my design, so I'd like to weed out the flaws while I still can. Constructive criticism is, of course, more than welcome.
A unit is defined as a single civilian in your kingdom. Each civilian represents a unit of manpower, and manpower is limited just as any other resource is. Civilians essentially spawn into your castle/town from thin air (unless I can find a better way) and sit around waiting to be used.
Any civilian can be given a role. Roles include all your standard medieval military staples (knights, archers) as well as less common non-warfare roles (merchants, blacksmiths). A unit is essentially a civilian which has been giving a standing role. A non-working civilian is mostly useless (or, at the very least, an untapped resource), so all civilians are expected to take a role.
To turn a civilian into a unit, you require the natural resources that unit would use. In the case of a farmer, you would have to have the required farming tools. In the case of a swordsman, you'd need a sword and armour. In the case of an archer, you'd probably need some kind of light tunic and a good bow. In all cases, you'd probably need to give the unit some kind of training in order for them to be able to use the tools they're given.
Once you have a unit, its purpose is less defined. Any unit can effectively be put in any position as raw manpower, but depending on the role itself, the unit may be more or less suitable for the task. For example, stationing a swordsman in a military training academy may result in a slight bonus to the production of other units (perhaps a slight reduction in training time), but of course this could also work in reverse (a swordsman placed in a farm would be wasted manpower; a farmer could fill the manpower role much better).
So why would you ever place a unit in a non-optimal situation? For one method of balance, there would be no real optimal situation. As another example, in a forge, a blacksmith may be good at smithing, but a swordsman working there may use his experience in sword fighting to help create swords with a better design (for a minor bonus in attack, perhaps). Alternatively, an alchemist working in a forge with a blacksmith could help refine the materials he uses (for a minor bonus in armour durability, perhaps).
Finally, there is the role of the army. Units can be placed in a mobile army for military purposes. Now obviously the ideal units for a mobile army are military units. However, alternative non-combat units could provide abstract bonuses. As another example, an alchemist may use his herbal medicine knowledge to heal soldiers more effectively between battles. Siege workers could repair siege engines such as catapults between battles. A travelling bard could provide morale boosts to the soldiers in an attempt to help them fight better.
What this all comes down to is versatility. Any unit can be placed in any role, with varying results. By offering a wide array of roles and positions, a player can be allowed to greatly vary his personal play style. Obviously, a lot of this would be possible to automate; it's good to give players the option to customize the positions of their units, but no task should ever be forced upon the player without their concept. Not everybody loves micromanagement.
Well, that turned out longer than I would have liked, but it's something to read at least. Like I said before, any kind of constructive criticism is greatly appreciated. With that, it's really late (and by late, I mean early) here, so I'll hit the sack. Thanks for stopping by.