About 30 seconds before I took out my tripod another photographer grabbed the spot I wanted! Doh! I ended up finding another spot, up on top of a small rock cliff that worked decently enough. I had some trees to contend with but got a decent enough composition without any trees. My spot was also much drier than where my friends were shooting from. The wind picked up at night and was blowing water from the falls all over us. I constantly had use my micro-fiber cloth to dry the front of my lens.
The battery of my wireless shutter release also happened to die just as the moonbow was starting. Trying to hand hold on BULB mode didn't work so I had to limit my exposures to 30 seconds :( It turned out to work decently as my D300s performed nicely even at ISO 500 and even up to ISO 640.
I didn't even notice there was a double rainbow in this until I got home! The moonbow was REALLY bright -- you could even start to see the color with the naked eye (which is usually impossible due to the structure of our eye failing to see color at night).
Nikon D300s w/Nikkor 17-35mm f/2.8 ED-IF AF-S:
28mm, f/5, 30 sec, ISO 500, Tripod
No HDR, no saturation increase, minor edits