Your quilt is amazing! I'm not great at coming up with quilting designs, but since there is a fairly large area of the leaf fabric, I would consider echoing the paper piecing designs in it. I would ditch the lines between sections, but not necessarily all the paper pieced triangles and spikes (I don't have the patience for that!).
I put figure 8's in the border, but if you can stipple or do some other fill, that would certainly work as well. I didn't draw it in, but I would stipple the parts of the leaf fabric in the middle that aren't in the echoed arches.
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Whatever you do, I'm sure it will look great!
Edit: That picture didn't come out as clear as I had hoped, but hopefully you can make out my red lines. If not, let me know, and I can make them thicker and repost.