One thing I missed are building requirements, this is something I really miss in KM.
For my group I created a list with some requirements for the buildings. I used Kingdom Size/Ruler Title (to encourage players to expand), Buildings, min City size and "other".
Most of the basic buildings (e.g. smith, granary, tradesman) not have any requirements.
More advanced buildings will have one requirement. The mist advanced one will have multiple requirements.
(e.g. a Libary needs an active Magister, Warehouse need 500gp base value, Slave Pens require that the Kingdoms alignment is any non-good, Granary requires at least one farm within 2 hex..., I think you get it^^)
Anyone else created requirement rules for their campaigns?
I personally complicated the system enough without adding building requirements for general town buildings. Where I did use requirements was more along the lines of skill requirements for certain types (like mines needed a miner or engineer or military trainer needed for certain types of units) and some of my homebrew buildings need certain buildings (seige workshop requires Military academy for example.)