We are looking for a light fixture for over our 8'x4' pool table. Are there certain guidelines to keep in mind, such as how much wattage is needed over this size table? We're thinking that we need something in the 48" long range which seems to indicate three bulbs. The light that we like the most (so far) has diffusers at the bottom of each of the three bulbs. Would that diffusion of light be good for playing? This particular light takes 100 watt bulbs. Does it make a difference whether we choose glass or metal?