Personally, I aim for a layout that has as little distortion as possible while still being humanly readable, the latter being a bit less significant. Depending on the complexity and importance of the object, I might use more UV spaces instead of trying to stuff everything in the 0-1 space. To me, it beats having to compensate by using extremely high resolution textures to allow for detail. I can't see any images of your castle but if I were aiming for realism then I'd go with multi tile UVs. If it works and it's clean, then it's done.