Ornate Vintage Frame needs idea

Here is a inexpensive garage sale find. A basically sound wood frame that needed a minor wood repair. It will eventually get a new coat of paint too. This gives a great base for a new project. I am leaning toward a leaded stain glass or a glass on glass mosaic. I have a 13 X 17 oval to work with. Does anyone out there care to share idea's of what should be created in this space? A flower, bird,....something abstract with light catching prisms? Please post!