Measure the distance from the seating area to the proposed location of the TV. A 32-inch television is perfect for a viewing distance range of between 4 feet and 6.7 feet, and a 60-inch set works well in a room where the seating is from 7.5 to 12.5 feet away.
Generally, bigger is better when it comes to flat screen televisions, and no one wants to sit so close they can see the pixels in the picture or so far away they miss the HD features of the TV. If the programs viewed on the TV will be mostly analog quality, sit further away from the screen.
Most flat screens have a 1080p resolution, so a good rule of thumb when buying a TV for any room is to place the TV from 1.5 to 2.5 times the screen diagonal away from the set. For example, a 46-inch HD TV should be placed from 5.7 to 9.5 feet away from the seating area to give the viewer the best picture possible. The viewing angle is also important, and an HD TV is best viewed head on. Be sure to place the set where the viewer's eye level is approximately level with the middle of the screen.