I would definitely do a narrow white border to frame the pinwheels, but then you have choices. If you want a color, I agree with NatalieF that turquoise is the way to go. Personally, I'd probably go with a neutral and then maybe pick up a color with my quilting thread. Black, grey, tan or white would all look really beautiful. I'm almost leaning toward black with a silver metallic thread for all the quilting. So sparkly!