Is that just a standard brown? I've thought about brown--but I'm worried about picking the wrong shade!

Hello,

Your roof on the picture looks brown. If so, I´d suggest you pick a colour that is in the same nuance as your roof. This way you can not go wrong on the shade. If the roof is not brown I´d suggest you to choose a brown shade that matches with the brown tiles on the actual house.

A copper roof eventually turns dark brownish gray over time. Here are some examples for color.

I was going to suggest a reall smokey grey, medium atleast if not darker.

If you want copper and can paint the roof, why not use a copper paint? It will not, of course, patina but you can choose a color anywhere from bright copper to dull copper to green copper with the choices of paint that are available. Actually ... I take that back - you can get a paint that will patina naturally... http://starscenic.net/metal-effects-primer-clone-.html