First of all I love it! It is kinda like the skateboarder quilt I am doing for my dgs. He had artistic license but now as I make it I am changing a few colors and such.
Secondly I would do a steam a seam applique cutting out the centers of the steam a seam to keep the pieces soft or use misty fuse to adhere the appliques in place.
Third I would then do a blanket stitch by machine in matching colors around the appliques.
I would embelish the large areas with machine quilting to add to the interest of each element!
Good luck it will be a wonderful quilt.
Luann in CT