I would say, I'd like certain things to be account bound. Account bound housing would fix the "mafia" and allow all alts to use the house in order to benefit the various things inside (like the crafting places), as well as making the armoire account bound for the special items and costumes.

For the rest though, I don't fully know: I'm not an achievement hunter BUT I'd like some sort of way so that all of your character can be united, like the Legacy System in SWTOR. In RP terms, you could roleplay a successor and such!