I like the purple idea iris colored maybe? or a soft blue cant go wrong. IMHO orange is too bright you have a ton going with the yellow. what about white sashing thin white border then a wider border of the purple or blue? p s lay out some colors between then a few blocks on top with say the 2 inch spacing? you can see what color you like best take a pic of each color then go look at your pics suprise you will like one!