Things like wandering NPCs that you can talk to and they will give you a heads up or something. Like say an NPC is in the Dreadlands, could have him warn you "Don't go over into the snow part, there are dragons". Makes it feel more realistic. Plus it creates a sort of unknown factor. I liked it when there was like one very aggressive/dangerous mob that is 'sometimes' up in an easier zone, makes people be on their toes. Also along this frame of thought, is to force people to use the lesser known areas of zones for quests or mobs.
Or...say, I always thought it would be neat if you get an HP bonus for sitting in a specific area, like inns or bars or such. Perhaps as well mana regen if you sit next to a lake. Or ooc abilities limited only to towns. Would be cool to have more area-based circumstances to help being immersed in the game.
I'll try to think of more, but personally I would like to see more of a roleplaying element added into this expansion. Though I realize this is easier said then done.