I see two kinds of blocks: one kind is made with TWO busy prints; the other is made with a tone-on-tone. I would make more of the second kind; less of the first kind. Your Sashing accomplishes two goals: sashing enlarges your quilt. Sashing tames your colors and design. A black or deep tone can make your colors "POP" even brighter. Take some yardage of various kinds, and lay your blocks on it while you work. Your own best instincts will decide the outcome. Is if for a specific person? Or purpose? That should influence your decisions.