For the stone walls it would be nice to have some pebble stones or grass/ plants along the corner where the wall meets the ground. Maybe you would like to bake the ambient occlusion for the decal with the walls imported, or bake ao into the diffuse.
For the rest, I don't know if you are planning to add this for all buildings, but if you do it would be nice to keep a difference between rural buildings (farm, corral, storehouse etc) and city buildings, maybe even military and civil city buildings.
The ones you've done already are looking much better now