Nothing like seeing clouds in the distance and getting a sense of their altitude due to shadows on the terrain. It adds immensely to the immersion. What I would also like to see are tall buildings in the distance (beyond the LOD limits). Think of it as mipmaps, but for buildings. In the far distance, you will only see select buildings taller than a specific height and with a certain density chosen by an algorithm (AI maybe?). You will be able identify cities from great distances, at altitude, due to a cluster of skyscrapers etc.