My decision now is whether to have 3.5" framing or 5" framing on the screen. The 5" frame would reduce the screen size by 10" yielding a 89" width and 102.3" diagonal viewing screen. The 3.5" frame would reduce the screen size by 7" yielding a 92" width and 105.75" diagonal viewing screen. So the smaller frame would yield 6% larger viewing area.
Throw will be about 12'. Viewing distance 11'. Windows have an eastern exposure. We live in a rural area with no street lights. We typically watch at night so there is very little light. We have blackout blinds, with very little light seepage.
The 5" frame is definitely the better way to go. I say this because it looks a lot nicer, increases the perceived contrast of the image, and most importantly, from an 11' viewing distance, I would get a 100" viewing area screen (and most definitely not anything larger). Any larger than that, and you are in danger of not being able to see the whole screen without moving your head left and right. The idea of a projection setup is to get a large screen, but not the largest screen possible. You want a screen size that will maximize the viewing experience. Projection screens already erase the problem that TVs introduce with having to settle for less than ideal size. With TVs, the bigger the better (simply because you really can't get a big enough TV unless you're looking to spend a lot of money). On the other hand, there is such a thing as going too large. Given the above, it's a no-brainier that you'd want to go with the 5" frames, since you'll have more than enough space for the larger frames with the ideal screen size for your setup.
In our Demo Room, we could have easily fit a 115" or 125" screen, but since the seating distance about 10% longer than yours, we went with the 108", since a larger screen would lessen the viewing experience.
Hope that helps.