I have a 120" screen and a projector with much less output than Aux recommends. A Sony HW40ES with 1700 lumens and screen gain of one. I use it set to output much less than that and it is more than bright enough. At full brightness it is way too much. My first row of seats is about 12 feet away and the second about 4 feet behind that.
Get a 16:9 screen and make a mask for when you want to watch the wider movies. Make a wooden frame and cover it with a non-reflective cloth like Fidelio Velvet - Black 1000. You can get it on amazon.
for wide movies I set the projector to stretch the picture vertically so you use all of the pixels, Then it is shrunk back down to the proper height with a high quality anamorphic lens. The picture is fabulous in both 16:9 and wide screen.
Good luck, the journey to get it set up is half the fun
Get a 16:9 screen and make a mask for when you want to watch the wider movies. Make a wooden frame and cover it with a non-reflective cloth like Fidelio Velvet - Black 1000. You can get it on amazon.
for wide movies I set the projector to stretch the picture vertically so you use all of the pixels, Then it is shrunk back down to the proper height with a high quality anamorphic lens. The picture is fabulous in both 16:9 and wide screen.
Good luck, the journey to get it set up is half the fun