Well, it depends really.
You need to consider how difficult it is to get around on your maps, the harder that is, the brighter it should be.
red: -102
Green: -102
Blue: -54
gray: 34
I like this effect. If your moon is out and large at night, this tint will give a slight glow to the edges of the water.
Really, its all down to tinkering. When the moon is out, the ground is lit with a beautiful blue tint (in real life) that works much the same as a bright flash light.
In a forest, the tint would be darker, and little moon light would reach through.
Tinker with it.
EDIT:
I also forgot to mention, for warmer nights, you could add value to the red color. Just one click to the right will usually do it, but try to balance it with the other colors so it isn't over powering.
The same with cool colors. Blue and green balanced with red.