The batteries died in my camera and I had to come back upstairs to put in new ones so I decided to post some of the choices I have tried for the alternating blocks.
I decided to come back and add to this post. The dilemma in choosing an alternating block color is that I have used every color in the rainbow in my 30+ blocks plus some have dark background, some have light backgrounds. So, choosing any one color, or any one value (light - dark) is difficult. Therefore my first choice was to try my vast collection of black and white batiks. I appreciate the comments.