Well I have been experimenting with daylight systems for my PRP artifacts and it really brings a model to life and with a view adjustments to the property, you are able to develop a variety of light effects from morning, evening and night.
Here are a few test examples I have done.
Normal settings with horizon and haze added to it.
Red and blue tint changed to produce a dark blue for a night sky, with a night sky map added.

Finally a night sky that turned out pretty wrong, but I thought it had a nice mythical quality to it.











