Day LOS should be slightly larger. In real life, you can see a person at kilometer or more, but for the sake of balance it should be slightly larger. In the day, you need longer warning before battle, in order to move over there using your map and add a bit of order to the beggining of the battle.
Night LOS should be as it is. However, inside your LOS, it needs to be slightly lighter. Seriously, whenever I am losing in any other game, I keep playing, but in Glest if it is night it is frustrating that I end up quiting. So yeah, for the aesthetics of the game, night needs to be about 30% bright insider your los. Also, make it slightly blue at night. In real life, because of the way the eye works, night does appear bluer, day yellower, and overcast days white.
A feature that would be REALLY cool, but probably not possible, is for LOS to be cut off quickly through trees. Not suddenly like a mountain is in the way, but for it to be shortened in that dimension.
Not sure if that last feature is possible, but everything above that seriously needs to be implemented.
