I usually hate using the literal colors to represent real materials. It just never looks good unless you're working in absolute accuracy (for example when presenting a multi-million dollar project to a client). For studio purposes, I've only seen a handful of realistic models that look good and are well built. I like the more abstracted look, so I usually go with a two-tone look.

Steel, framing, windows - wood
Concrete, brick, floors, walls - thin cardboard
Earth - heavy grayboard

I've pretty much done this for all my models. My favorite is an entrance detail I did of a fire station.