It would be nice if they could have an Oblivion-like level of detail when it came to NPC schedules, but I think that's something that would be a lot less noticeable in a game like this, especially for generic NPCs.
It would be cool if there were a few NPCs that exhibited strange behavior if you paid enough attention to them, such as late-night benders.
I do really like the idea of drinking buddies, or more relationships between NPCs in general, even if only for named characters.