benq w7000 screen size recomendations, please???

I was hoping to get some recommendations on screen size for this PJ. I set it up at 110" sitting about 13.5 feet back. it just didn't feel that big!

I'm also going to have seating behind the front row...so that will be close to 16 or 17 feet away.

for movies, the room will be pretty well blacked out...but another primary use is going to be for football games in dim-lit situations.

I just put up a bit 12' by 8' black floating panel above the area where the screen will be positioned, and the screen wall will be a very dark blue. I will also have a black rug on the floor in front of the screen.

it's web based...and awesome. you can render your layout in 3d as well: http://www.floorplanner.net

8ft cielings. thanks!

about how large can I still go....with some ambient light....before I start to get a noticeably dimmer picture?

thanks, guys. this is much appreciated.

thanks, coderguy. will I notice much difference in brightness going from 110 to 140 or 150 with some ambient light? ie, daytime, shades drawn...bar room type lighting.