Sawtooth border added to appliqué quilt

I spent a satisfying day sewing yesterday, adding a sawtooth border to my appliqué quilt.  The colored triangles are mostly the very dark blue that predominates in the appliqué, but I also used a smaller number made from the other colors—green, light blue, brown, and orange/red (more visible in detail below).  The next step will be a 6" border, repeating the light gray background with some kind of appliqué design.  So, the next step is to figure out a border design that will work with the variety of motifs in the squares.