I quilt the top half of these before I sew the straps and pocket on. For batting, I'm using some flannel that started pilling the first time I washed it. I knew it wouldn't be good for a quilt border like I wanted, but for batting inside the tops of these totes, nobody will see it. Nothing fancy for the quilting either, I just lay down strips of masking tape in nice straight rows, and sew between the tape. You can barely see the lines of stitching if you click on the picture below.
My Siamese inspector is in just about the same position as last time. Predictable, isn't he? I hung both totes on the doorknob when I finished taking the picture above, and Toby was so sure I'd hidden something behind them, he had to check: