Triumphs
Warning: slightly frivolous idea ahead
It might be fun to allow your armies and/or generals a "Triumph" if they succeed in some large feat: defeating an invading army, conquering another kingdom/empire, completing a quest, or even succeeding in some great act of diplomacy. It might be cool to see your Army of Light/Army of Doom marching/tramping down the city streets bedecked with flowers/heads of their enemies.
Maybe throw in some interesting costs and bonuses, to boot: costs x gold, provides temporary increase of y% to morale for the city and participating units. If foreign diplomats are in the city their kingdom/empire will hold yours in greater awe.