I know it's a lot of work, but I always love the quilts like this where they do a different filler for every block (think Leah Day). I would pick a matching-ish color for most of them because with that many different colors of fabric & such busy prints, short of picking clashing obnoxious colors, the quilting won't be visible. The fun thing about fillers is you can close to match the fabric & use them to create texture rather than a separate design element. I'd limit the colors to:
dusty purple
antique gold
muted brick red
(could also add: blue-grey and/or dull green, if available)
Then I'd just either SITD for the black sashing, or at most run a single line (straight or squiggly) down the center of each strip).
In the border, since it's so busy, I'd just work with the print itself. If you wanted to add some pizazz, you could trapunto some/all of the large flowers in the print. But really, I'm not sure if I would because short of picking a bright, attention-grabbing color, I really thinking most of the quilting in the border will be close to impossible to see.
Really love all the beautiful fabrics you included. I think they should be the stars of the quilt! While there are ways to force the quilting to show up, they would take away from the beauty of the fabrics & piecing. If you really have your heart set on quilting a particular design, I'd maybe switch out the border to solid black & quilt a design in the border.