Well, for me, what makes or breaks me playing a game is housing. Yeah, it sounds weird, but that's what i like, a place to live. So here are my suggestions on how to make the housing better.
1) More items to allow in your apartment. Up the limit from 10 so you can actually have a populated apartment that doesn't look so empty. Maybe have a system where it costs people money to upgrade how many items they can have.
2) Have a way that the owner can duplicate keys for others to enter. Or...have it set so they can add "allowances" for ther apartment, allowing their friends to enter while not in a group.
3) Have all types of furniture available. Beds, couches, tv's, tables, etc...this may be already implimented, but I'm not sure, so I added it anyway. Just so it'll look like an actual apartment.
4) Possibly have lighting control where you can adjust the lighting in the room and in the closet.
5) Just a minor thing, but possibly have a command like the "sit" command that will let you lay down. So if you have a bed, you can lay down on it (makes it look more realistic).
6) Maybe make it so you can have an aquarium in your apartment. At the furniture shops, buy different fish to put in it so people can have a variety of fish swimming around. (Just thought I'd be neat.)
7) Have missions randomly (possibly rarely) tack on to missions for furniture that is only available through a mission, ,meaing you can't buy it at a store normally. This, in theory, would promote teaming up to take on missions if you added it to only the team missions.
Hmm...er...some of that went way out there, but I think it'd be neat. If I think of more, I'll tack on. But for now, at least take it into consideration if you will :o)
Take care!