I have a 106" screen in a room almost 22 feet long. The Wii works very well. When wiring my room I ran some Cat5 to the same outlet as the center channel speaker. All my equipment, including the Wii, is at the back of the room. I used the Cat5 to extend the Wii sensor bar which now sits on top of the screen. It does lose a little sensitivity to the back of the room but overall it works from anywhere in the room. I had played with battery powered sensor bars (with a suitable wall-wart hacked in) but had no love. It worked but they had less range than the Wii sensor.
It's easy to splice into the Wii sensor bar. It has two very fine wires, positive and negative. The wires have a coating for insulation which has to be melted off. Then you can just solder. Mine now runs through about 30 feet of Cat5.
Sensor bar is a misnomer. The bar just has two IR light sources, the Wiimote is the sensor. I'm going to try building a brighter one with separate lights so that the width can be varied. Should be fairly trivial, just need to put butt in gear.
