I think one BIG battle would be nice. The Battle of Bruma was dissapointing, even Bethesda themselves admitted that they would have liked the battle of bruma to be bigger, but due to technical details, they couldn't have many npc's on screen at the same time.
This led me to think of a way to do a BIG huge battle without having too many npcs on screen, (warning long read)
I thought about a caslte seige, basically the player is tasked with defending the castle and you have a few moments before the battle to set up some defenses which will help determine the outcome of the battle (of course the battle doesn't necessarily end in success, you could fail) When all is set up the player goes to the walls and sees in the distance 2 huge armies about to fight. Of course this isn't npcs, it's just some low poly soldiers with animations applied to them, anyway they start fighting and it looks cool, at least from a distance.
The player gives the order to fire catapults or whatever and sooner or later some soldier comes by and says that the enemy is trying to break down the gate. The player follows the soldier and just about right when they reach the gate a huge monster breaks down the gate (I can't help but imagine the mountain trolls from LOTR) The player is knocked on the ground. The gate and part of the wall is laid in ruins and you cannot get our through the gate anymore, however the enemy can climb the other side and get in.
After the player defeats the monster he get a little time to recover before waves of enemies come through the gate. The player has to fight a couple of waves and finally some kind of boss creature arrives, but the player is forced to retreat deeper into the castle where more enemies attack, this time we want to upgrade their attack a little, it has to feel intense and overwhelming to give the illusion that this really is a seige and the castle is surrounded by enemies. Again the boss creature appears and the player is forced to retreat deeper into the castle and ultimately into the main hall where he has to make a last stand and finally fight the boss creature, when said boss creature is defeated the remaining enemy forces will flee in terror as they're getting shot at with flaming arrows and fireballs