Really, 10 feet isn't wide enough? You could just move closer and not change the screen size and keep the bright image you have now.
For example, if you sit 13.3 feet from the 120" screen, you have a viewing angle of 41.2 degrees
If you change to a 160 inch screen and stay at 13.3 feet viewing distance, your new viewing angle is 53.2 degrees.
You can achieve the same 52.3 degree viewing angle with the 120" screen if you simply sit 10 feet from the screen. And sound quality is likely to be better when you are 10 feet from the screen also as direct sound from the main speakers and center channel will be a bit more prominent (compared to refleted sound energy that is delayed and "stirred" considerably compared to the direct sound from the speakers). No cash outlay for a new screen and a high probability of better sound quality in the bargain - just move 3.3 feet closer. Of course, that may not be possible in some rooms (risers or other features, etc). I use a wider viewing angle than both of these examples with a much smaller screen... ON PURPOSE. Because of the sound quality issue. The impact of viewing the movie on a smaller screen with similar viewing angles is exactly the same as the impact you get from a larger screen with more distant viewing seat because the viewing angle determines how large you perceive the images, not the size of the screen.