So, I was thinking it would be cool to have a stand off in a way. Like both teams have one castle and they have to defend their own but attack theirs. At the same time as that. you need people crafting siege equipment (catapults, siege towers, etc). Have the front doors be attack-able so you can break it down with catapults. Also have Npcs to fight through so it will be an epic fight.
Also, The materials for the siege/ defense equipment should have all of them in the castle.
I would like the devs to implement this as I think it wold be awesome.
P.S. I think a good way to capture a castle would be A) capture the flag or B) assinate an Npc King