I’d like a village outside my castle where merchants collect and NPCs wonder around. So occasionally I can exit the castle and take a breath of fresh air. This would make my kingdom feel more like a kingdom and the castle less lonely (although the castle is, indeed, filled with creatures and a pub).
Imagine going South, South from the War Room and you’ll get to a green area with wooden stalls and birds tweeting. 8)
Edit: I see this post in General Forum picks out a similar idea: https://forums.thylacinestudios.com/t/470