I must be the oddball, because I'm a fan of a single color on a Road King Classic. I think about it this way........ you have black cherry, lots of chrome, lots of black leather, and big whitewall tires. In effect there are 4 different colors going on. Now add another color to the lower half of the tank and you'll have 5 colors - too busy for me.
My two cents.
Solid colors for me too......and here all along, I thought I was the ODD BALL.
It looks good with the silver, another suggestion is black pearl or a charcoal of some kind, the Ultras & Classics used that combo & I always thought it looked real good. It depends on how much you want it to stand out, the lighter the color the more it will stand out.