Ideal Screen Size for Theater? 2.35:1 or 16:9?

Aux- 
Thank you for the info.  
I have 15.8 feet available to me for width but I think I will go with something smaller.  I was thinking around 11 feet wide plus or minus a foot.  I have had people (in the business) try and talk me into a 100 inch diagonal screen to which I say, I would rather just do a 90 inch TV and forego the cost of screen and projector.  Since I am doing the projector, why wouldn't I go bigger?  
I have the ability to control the light in the room so I don't think it will be too bad with ambient light.  There will be some light from the sides and rear but not too bad.  I think in order to do the larger screen with my speakers (48 inch high) I need to have acoustically trasnparent material or else the screen will go all the way to the ceiling which seems too high.

I think I should probably do the 16:9

Are the grey or black superior to the white in any aspects other than ambient light rejection?  

Also with gains of 1.5+, do you see any bright spots in the center or banding issues of any type? or any hot spots?


Stewart keeps coming up as the brand of choice for serious people looking for a nice screen.  I have looked online at screen innovations and their 7 series motorized looks sweet.  Do you or anyone else on here have experience with any of the other screens not named stewart?

Also- what do you guys use for projectors? And, are you happy with it and its performance and reliability? 

Greg- 
I have seen some theaters projected on the painted walls.  They don't look that bad.
These are my reservations with white painted walls for projectors.
You are limited to white.  If you want to paint your other walls a different color, the one you project on would have to be white. It would look odd to me.  Also, I'm sure the white paint used would not look good in a room as it would look very sterile like a hospital.  

As for projector, I am looking at the sonys, epsons and wolfs.  I am not opposed to using other brands but they are the ones I am most familiar with.  Sony is what I would really like due to the fact that they are 4k but their cost is somewhat out of control.  But the main fact is that I am looking at 2000 lumen+ if I can afford it.