one of the things i really liked about age of wonders (my go to tbs) was your ability to truly turn your cities into strategic strongholds, with automated defenses, stocked with canons, and with reinforced gates that the foe had to beat down before they could force their way through that chokehold into your troops, all the while your archers could rain down pointy death upon them.  Im not sure if its possible, but making the tactical maps in city fights more open to being set up through the walls upgrades, rather than just a defense bonus, would make it more a strategic joy, im thinking.