I have been working on nighttime imaging for a while, trying different exposures and post-capture processing.
This image was one of my first attempts. I hiked in to a location with very little ambient light, actually I went there to capture meteor images last August. I shot this at f3.5 at 30 sec and 800 ISO, using a Canon t2i and an 15-85mm lens. I tried using various settings of ISO, but had the idea that I should not get much above 800-1200iso.
The image was shot in the RAW format, opening it in Photoshop I made several changes:
The noise reduction and sharpening was used heavily to reduce the graininess
Lens distortion correction
Fill light was used to brighten the image and Recovery to decrease the brightness on the tent
Vibrance, Clarity and Contrast were also significantly increased.
I saved the image as a jpeg and opened it in PS (I was using CS5 for this image) and went on to select the sky, and using Levels brought out the contrast by moving the slider to the right (to the start of the peak) and to the left down to 220. here is the result:

This year I got myself a new Canon 6D and went to Washington Pass, along the North Cascades Highway to take pictures. I was careful to choose a night with clear skies and very little moon.
This image was shot at 8sec, f4.0 and 25,600 iso. There is a setting on the camera for “High ISO Noise Reduction” and I set this to high. I tried to keep the shutter speed low, 10 sec or less, to make sure there was no blur from movement of the earth, etc.

Again, I shot this in the RAW format. Photoshop CS5 was not able to open the RAW images I shot with the new Canon 6D, so I had to upgrade to CS 6…
Here are the basic modifications made to the RAW image:
The sharpening was used heavily, BUT no Noise Reduction
Lens distortion correction
I increased Vibrance, Saturation and Highlights
Here is the result:

Going back to the image later I felt that there was still to much graininess and so I went back to the RAW image and greatly increased the Noise Reduction, then I saved the image as a jpeg and opened it in PS (I was using CS6 for this image) and went on to select the sky, and using Levels brought out the contrast by moving the slider to the right (to the start of the peak) and to the left down to 220. Here is the result:

I am much more satisfied with the version.
Please feel free to let me know which variation you like the most, and if you can, why!
And if you have any ideas, tips or suggestions, I am very interested.