Also your local model plane flying field -- look for planes that you like; if you see something that makes you go "zing!" then copy it. Or take a swing through the toy section of your local department store, looking at the airplanes and space ships (and, IMHO, hot pink stunt ships with Barbie heads for pilots is an entire genre of decorative themes that has not been adequately plumbed -- maybe about 3/4 black, with generous trim in hot pink, and Barbie wearing a color-coordinated headset).
Or paint it red, white and blue (or whatever your national colors are). The colors look good together, and you can't go wrong with a flag scheme.
I find that when I'm in a dilemma like this I'll just forge ahead, even if I think I'm not going to like the results. At best, when I'm standing there holding a can of paint in my hand and looking at all the bare primer what I really want to do will crystallize. At worst, I'll end up with an ugly, but flyable airplane.
Or make a rough three-view of it to fit a regular sheet of paper, make copies, then steal your kid's crayons. Try a whole bunch of different schemes -- horizontal stripes, vertical stripes (ugh!), swirls, swoopy lines, etc. Then show them to your wife and use the one that she lingers over for the longest (unless she's laughing out loud when she's doing it, of course).
(Or black, hot pink, and bright orange. You may have to accessorize Barbie's cockpit with a bong if you go that far, but it'll certainly get the judges attention).
(Or black, hot pink, bright orange, and Ken in the cockpit with pink hair. Cockpit accessories left as an exercise for the reader.).
(Or black, with your AMA number in charcoal gray as the only trim, and Will Smith in the cockpit wearing mirror shades and a black suit).
(I'd suggest Porche Indian Red, with a chrome stripe down the center line of the fuselage, and Grommit in the cockpit -- but that one's mine, mine mine! http://www.youtube.com/watch?v=dy9QeosTh7w&list=SL).