I am knitting a blanket. I have two colors already. What should my third color be?

The pattern is going to be a repetition of stripes. The first stripe is royal purple and about two hands wide. The second stripe will be 3/4 of that width and the third stripe will be 1/4 of the big stripe. I plan on making one of the stripes a creme orange. My question is should the orange be the middle or small stripe and what the other color should be.