There's two things to directly consider when setting light distance, the intensity and the coverage. Light intensity decrease's quickly, square the distance and divide by the number (ie. @ 2' it's 1/4 as strong as @ 1', @ 3' it's only 1/9th), so the closer without burning the better. The closer lights get the less area they'll cover and as plants can only use so much light depending on how much; water, co2, ferts, etc are available, there is a point of diminishing returns.
So the just of it is, every garden is different and to get the most out of your space you need to pay attention and adjust to the conditions (which change over the year unless you have a really fancy, totally climate controlled space). For fluorescents I'd generally say 4-6" is a good starting point, from there try it higher to see if they stretch, lower to see if the leaves crinkle from heat, etc.
Some will get great results really close, usually they'll have lower temps and higher humidity which reduces water stress so even seedlings can use the higher light levels. Right now at my place I'd give them a lot more space as it's hot and dry from the furnace running, so they'll already be stressed without any heat from the lights. Which is why you'll see such contradictory answers, neither is right or wrong, only right for their conditions. My best suggestion to new indoor growers is to learn as much as possible about how the environment effects the plants. Control the climate and you control how the plants grow as they're solely reacting to the conditions around them.
