I know exactly how you feel. I was in a similar predicament when I was looking at painting my Mach... But be careful about trying to pick an "uncommon" color. I too was going to go with something more "timeless" like a medium metalic blue, calypso coral, or black, but then decided I wanted something less common. I thought maybe a nice school bus yellow or maybe Grabber Orange or Grabber Green, until I saw a Boss in my Mach's original color (Bright Gold Metalic). It looked fantastic, it was unique but classic color, so I went with it.
2 years later, Bright gold metalic seems to have become very popular and almost common. I've seen several (10-15) different '70 Bright gold metalic Mach 1s show up in magazines and on various forums and on eBay. Admittedly, its hardly as common as most other colors, but I think its become a poster child for the "classic, timeless, unique" color.
My point? If you choose a color that is tasteful and attractive, eventually it will become popular, which is probably a testament to your good taste and sensibilities. At least thats how I look at it.
BTW, sure, red is pretty common, but I think its a good choice if you pick just the right red. Something with a little orange, maybe even a multi stage with a yellow chrome base.