I think the fight to the death mode in city sieges is a bit overkill. Once the wall is breached, the enemy army in the city has the numerical superiority, the general and all high discipline units are dead? We should see militia and peasant units surrendering if the invader is the same religion. I think the fight to the death thing should mostly be if the invader is a different faith and thus more likely to exterminate the town.

Also it seems like, in cases where a settlement is besieged and there aren't any generals, knightly or elite units in it... just peasants and militia types... AND they are massively outnumbered, the defenders should try to negotiate the city's surrender. This wouldn't happen all the time, but it makes a lot of sense. And it would be a nice replacement for autocalc attacks that kill 300 defenders and only 4 attackers. Such a surrender should also not invoke papal wrath as an extra act of war either. There would need to be diplomatic options including agreements not to sack or exterminate the city. (Granted, you still COULD, but the reputation and pope meter hits would be astronomical doing so in violation of the agreement.)