I think in today's game, that is based on the environment/climate that you are in.
Many games have areas that are short distance viewing, or a haze or fog about them. I agree munge, that Pantheon should include a lot more "atmosphere" to certain regions of the world, to give them a personalized feeling.
I prefer the fog method as well though sometimes the fog can create more problems then it causes. We are constantly tweaking the fog and draw range in each zone because each zone has is own unique topology and climate. Some zones may share similar climates but they will be unique in that some may have more fog in the distance with a shorter clipping range then others, or it maybe have more of one weather system then another. I know its starting to sound like Im talking about weather now but fog plays a very integral roll when it comes to weather.
Bottom line is the fog and draw distance will be based on the zones climate and topology and of course the draw distance will always go beyond the fog so your not getting the clipped mountain's as you pan the camera.
