While the limit factor on a room use to be the width, I rather prefer limit screen height going with 2.35 AR screen, since as everybody else going for cinema as a priority, like the scope filmed movies having that better epic and more inmersive feeling over 1.85 ones.
But Im wondering now if that fact on the most inmersive definitive AR may change. Now IMAX operating equipment are getting cheaper and more affordable, and the best commercial cinema experience are actually on IMAX, where some movie scenes (dark knight, inception) are shot on the big format (65, 70mm) on 16:9, switching on these movies from 2.35 to 16:9 for IMAX shot scenes. I guess theres no too much left till complete movies may be shot entirely on that format.
So that may lead us to re-think again, on which one of the ARs will be the king for the best cinematic experience.