Optoma HD8200 Projector Screen Recommendations
I see two ways of looking at the HD8200 and matching it with a suitable projector screen.
The first are for those people who are really completely focused on movie watching. For those folks, I'd really recommend a high contrast gray surface. The lighter gray of such screens are fine, such as the Da-lite HC Cinema Vision. That type of screen will complement the already pretty impressive black levels, lowering them still further. The HD8200 may still not match projectors like the Mitsubishi HC7000 or Epson 6500UB for blacks, but should be close, to say the Sanyo PLV-Z3000. The HC gray screen will lower those blacks that small extra amount, and will also help with dealing with minor side ambient light.
For those concerned with viewing a wider range of content, I would say, that if walls are dark, the HD8200 may pair up better with a good white surfaced projector screen with some gain, such as the Carada Brilliant White, Stewart Studiotek 130, or other screens with gain in the 1.3 to 1.5 range. You can, of course, go higher gain, but you start getting into a more limited viewing cone and a little hot spotting/corner dimness.