Thanks for your input! I will take the advice given and add more windows in the corners. Today I ordered gray/grey fabrics since the fabrics seen through the windows are white or ivory; it seemed that black framing would be too dark. Hopefully there will be enough contrast between the three shades/texture to allow the ribbons to stand out enough.
My "window" frame fabric is already on the way, along with a new color card! Kudos to Hawthorne Threads for such prompt service.