Great guesses on what border fabric I chose! If it didn’t take so long to finish the panel, I would want to try them all out!
My border is a black-on-white polka dot. As I was embroidering I was actually thinking of a multi-color African print for the border, but somehow the polka dots jumped out at me when it came time to add the border. Then I decided to quilt the border with seed beads. … Speaking of seed beads, today’s tip is about choosing batting for beaded quilt wallhangings.
Check out the detail below. There are two different batting effects at play here:

I used black wool felt as the batting for the embroidery panel. Wool felt comes in several thicknesses and many different colors. (Choose a matching felt and if the fibers beard a bit you won’t notice it.) Wool felt is easy to pull the needle through and supports the beadwork very well.
The border was an experiment. It has two layers of Warm & Natural cotton batting. This also supports beadwork well, but gives a different effect. Look carefully and you’ll see that the nylon beading thread carried between the layers creates a bit of puckering like you would get on antique quilts (and new ones as well) when the batting shrinks in the wash. If you’d like the puckered antique look, but don’t want to wash your beadwork (dyed beads can bleed in the wash), this would be the way to go. I haven’t tested this technique with a single layer of cotton batting yet, I needed the heft of two layers to support the wool felt batting in the embroidered block.
The more beads you sew onto your quilt, the more support you’re going to need, so consider all your batting options (including non-traditional ones) before you begin beading. You could even sew a handful of beads on a sample sandwich or two to test the battings out first.
I absolutely love the way you have done the border. The beads where the border meets the body of the quilt is gorgeous and the beads on the black dots compliment the rest of it perfectly.
I also love the beading on this. It’s a perfect accent.