Maybe you could consider texture arrays so that you can easily change textures without the UV wraping trouble ( that i use to have 
)
Texture splatting is also kinda must have so that you can easily draw stones irregularities/differences on the walls. I implemented this in blender in unity for Carcassonne 3D but it became a no-go for realtime rendering on low-end android mobile devices 
But if you don’t plan to real-time render your meshes on low-end devices this really gives a great visual enhancement ^^
Just because castle walls suffered from time and armies attacks…
I guess it could even be randomly set up procedurally with a noise texture and building heights with a simple rule: The higher is a building the more probable it fell and was rebuilt
as an illustration here’s one wall from carcassonne you can see on google street view 
Okay for the ‘spruce up’ 
it’s a really good method ( i’d say it is IMHO the best one ) when you don’t need to model inside rooms and corridors. Care not to fall in the trap i fell: scene from models lib where finally each model was different x))
I don’t know what will be your final renderer, but if it’s intended to be kinda realtime, you should also consider AO global map.
For still pics, AO is natively rendered by Cycles, then all is okay. But in realtime, AO is extremely GPU stressing. What i do for carcassonne 3D is huge maps of 8K where i store my walls/towers AO bake ( and dirt ). This way the final rendering GPU only have one diffuse map and one dirt/AO map to blend and render. Wich is pretty fast to render even on slower GPUs.
happy blending !