I like to use items that are meaningful to the homeowner on ledges such as these. Do you have any large, interesting boxes, trunks, baskets, vases? I have used boots, hats, antique trunks, etc., when decorating ledges. You don't want too many items, and you don't want to block the light you are getting from the windows. Do a search on Houzz for "ledges", and see what strikes you.

Your kitchen has a very zen balance and clean lines..perhaps a big fat Buddha in the center and nothing else

If your Buddha was the same color of your tile he would seem to be a part of the design while bringing a feeling of serenity as well