As for lighting it would be cool if it depended on if the moon was full or half. Clouds would make it darker and think of hw cool a dragon fight would be if it was only iluminated by lightning strikes, or when it shot fire at you!
That would be incredibly awesome. Pitch blackness with heavy rainfall. Ocassional lightning strike and thunder. Only way to tell where the dragon is would be if it were flaming up for another strike while flying around. Gives it more of an increased feeling of accomplishment instead of only waiting for daytime to fight them. I fully intend to fight the dragons in as varied climates and scenarios as possible. To liven and change things up greatly.
Especially would be nice to see the stars and moons in the night time sky. Could be the basis for how much the particular game cell the PC and immediate player area is illuminated.