^ You say that you would try shooting ambient. but if you shoot purely ambient then isn't it possible (likely) that the color of light filling the room will be the color of light landing on your subject's face ? If that is the case then when you go to correct so that the face isn't, say, fluorescent magenta (!), won't you be almost completely sucking the color out of the background as well ? This obviously isn't true if there are different colored lights in different portions of the room--and that may well be the case here. I've just always found that when I wanted to preserve the color aspect of the atmosphere of the room the way to do it was to (under)expose for that background (dropping it a stop or so to get richer colors) and then to add flash to expose the subject in front of me.