I have struggled for months with my environments. As a lone dev I don't have the manpower to do things the traditional way but I still need near photorealistic results. Outside of a few test rooms, everything has been in graybox.
Finally think I've solved it. I'm building "smart" materials that can be applied within Unity per triangle. Each material is a procedural system that can then adapt to the geometry of the surface and place 3D objects as needed. For example if used inside a modern house, it would automatically add paint, molding, wall outlets, light switches, and pictures. Every element can be customized by hand as needed.
I can then add more dynamic "clutter" by hand the traditional way.
Have you got any screens of some of the environments you've made using smart material?