One change I'd like to see as we move forward to 1.1 and A/B is an expanded use for recruited heroes. I don't know about other players, but I typically end up with lots and lots of recruited heroes.
I like that there is diversity in them - some are effective only if in a settlement, some are best left on the field, and others it just doesn't matter, although there is a risk to losing them in battle.
For those that have good stats and are imbued, I often let them lead their own armies after exping with the sovereign a bit. I think as we move away from summoned armies and towards combined arms, it would add a lot of flavor and tactical consideration by allowing players to designate a unit or hero as the captain of a particular stack of troops - this in turn confers some ability (or even penalty) to the unit as a whole.
For example, what's-his-face Jasper the Farmer. Let's say he confers a bonus to the effectiveness of Peasent/peons in his army. Raline the Weaver - units under her lead have better cloaks and boots, and see a mild increase in move and armor. Ninuues....or...niu....whatever. His army gains a resistance to cold/ice spells and deal a small amount of additional ice damage when attacking.
Most tech researcher heroes and adventurers would confer a bonus to armor, attack, speed, move, and/or terrain effects of various magnitude; or resistances or bonuses to various attack types and directions. Arcane researchers would provide resistances to magic, possibly increases to effectiveness (or blanket decrease to the entire field, for some of the anti-magic story heroes). Merchant led armies might find themselves with better equipment, or better able to salvage items after a battle for gildar. Thief and assassin led units might deal better damage when attacking from a direction*.
*Because of the way tactical battle works now, and because facing would be a pain to implement under it, I would propose the four cardinal directions be 'Direct' attacks, while the 4 diagonal directions be 'flanking' attacks. Ranged and magic would be separate categories.
There's also that wilderness-ranger adventurer guy... perhaps bears and such are much more effective under his control (but his units suffer when guarding cities). Bards could swing moral much more heavily, as well as downtime-healing. Maybe administrators provide better movement, or increase the attack and defense of grouped units more. Penalties are also possible - there are Raeguile, the clumsy adventurer, and that one insane girl adventurer... the bitter royals, and so forth. One captain per army, regardless of how many heroes are in it. No flip flopping between different heroes as captain in an army to obtain advantages as the upcoming battle seems to need. And of course, if the captain dies, that's a massive moral hit.
Under this scheme, researching adventurer techs could unlock or increase the effectiveness of these bonuses.
Additionally, I'd like to see some sort of passive leveling system in place for units and heroes that are assigned to guard settlements. These units otherwise don't gain exp - and consequently can become rather useless as time goes on, except as exploration fodder (or wagon line fodder). Seems kinda harsh. Bandits and the like are out getting exp or what have you but not the city guards - and thus they are also at a disadvantage when attacked by armies that have been killing stuff.
You are afterall, paying their wages. They should be doing something. Perhaps the Experience-line of warfare tech could be changed to the rate or amount or cap of passive exp that can be gained. As opposed to creating veteran troops, but 60 turns later =p You'll get them sooner, and 60 turns of guarding the city later, they'll be veterans... basically the same effect, but it has the bonus of dealing with the issue of pumping out 12 man veteran squads in 1-2 turns with certain building/tech combinations.
