I like the whole day and night thing, gives the game more depth imo. Moslty though its just doors locking and vedors dissapearing for 6 hours. What if you gave Night time a little more meaning, Like at night a few wandering Thug/rogue/bandit mobs spawn inside some citys. Mostly low level ones, with low level gear, as to not inconvience the new players. Maybe a few higher level named ones as well in more out of reach locations. Just an idea. You could base quests around it.