I initially pulled a traditional red and blue for double borders. Now that I am looking at the picture of the finished flimsy though, I see a huge lime green band on the large central diagonal with hot pink bands on either corner. I might pull something along those lines and see if it is too bright.
I am linking up with Oh Scrap and Slow Stitching Sunday today. You should visit and see what everyone else is up to before you get going on your day.