Neil, I have a green RST, and as I use it as a commuter, daily ride, credit card tourer, shopping cart, etc. I like to keep it subtle. Bright frame colours on a bike (for me) shout lycra and shaved legs, and catch thieves eyes more at the bike rack.
As Julk says, it's a very personal choice. When you are riding it, you won't see much of the colour anyway. Will scratches from using the bike show up more if the bike is loudly coloured ?
cheers,
Simon