If you go to the website crutchfield.com, they have information that will guide you on the optimal size tv screen based on the viewing distance.

My projection room seating is about 17' from the screen and I have a 133" screen. I wouldn't want smaller.

I'm not sure how the Wii would look on a big screen projector, resoluton-wise. Plus, depending on where the projector and screen were located, you wouldn't want to be playing a jumping up and down game and getting in the way of the projector. Plus, do you want to rack up hours on the projector's bulb playing wii?

Lastly, you know ambient lighting can wash out a projection screen's picture. So depending on how much light will be on when playing Wii as well as the location of the light relative to the screen and the player's eyes, not to mention the type of screen...lots of variables...you might lose some fine game-playing screen details that could frustrate the players.

I'd recommend the projector for movies and quiet TV, and a smaller flatscreen for Wii.

FWIW, several screen manufacturers will send you screen material samples. I took all the samples, probably 15 in all, and taped them up on a sheet of plywood primed with white Zinsser primer. We used that to evaluate screen materials for both movie watching and TV (mostly sports) watching.

When we have a crowd over for football, we prefer to have some lights on in the room, so the Dalite High Power worked best for us.