Looking at the noble demands, I thought it might be interesting to ask about the feasibility (although not so much the necessity, I think it's alright at the moment) of attaching a commoner to a noble as a designated "servant." The idea being that a given commoner is in the direct employ of a particular master and sees to his or her desires with some kind of priority.
In general this wouldn't have any effect, but if for example a good the noble wants is available in a stockpile, his servant would prioritize getting it to his master's room or whatever at all costs. Or if he's a mason, engraving in his master's owned areas before other designated tasks, etc. Basically a workaround to the priority of tasks that would help keep nobles happy by assigning dwarves who will generally be looking out for their bosses first and foremost.
Certain noble types might also grant certain abilities or duties to their servants, perhaps (like a sheriff granting deputy status to a military servant). Given restrictions on population it might not be such a good idea to add servants to lists of demands that nobles have, but a ruler (like a King) might rightfully request a few dwarves be assigned to his welfare as a status thing. Maybe even get upset if another noble has more servants than he does.
Just a random thought.