[hollywood_steve]

Do you think it is necessary to have different room to track in so that there are different "ambiance" for different instruments?

Just the opposite; the main goal on any multitrack recording I do is to make it sound like every instrument was tracked in the same space, and at the same time. I can't imagine a situation where I would want different room sounds in one recording. That's why I'm always confused when folks use a bunch of different reverbs on a song; are they trying to help the listener catch on that the guitar player and the drummer have never met and recorded their parts weeks apart? A single reverb, or a single room are a necessary foundation if you want the end result to sound anything like a band playing together.