I'd like to see the towns be different at night, and also have some different encounters at that time. But i don't want to quest that's dependen on day/night cycle. I also like the idea with muggers and thiefs at night, it would make sense. But of my biggest problems with BG2 was the attacks by muggers and slavers after i'd become high level. Which didn't make alot of sense as they normally died in almost no time at all.
Well you could do it in the same style as Pathfinder does it. Humans get one extra skill point, one extra feat and +2 on a stat of their choice. (Not that it's going to be pathfinder rules ofcourse, it was just the general idea about giving humans a bonus)