Traditional Amish Backing is to have muslin on the back. One quilt means all the love and use is put on that one quilt. If you make two it will spread out the wear, in my house we call it loving them. Twice as much love with less wear. I would make two quilts. It is wonderful that you have these to cherish.
One common way to quilt is "stitch in the ditch" meaning you sew through all three layers in the seams of the little blocks. That way the quilting is seen less and the sewing pops more. It's also much easier than trying to make a complex pattern over the top. Stitch in the ditch could be done on a sewing machine or by hand because the quilting hides fairly well in the "ditch". Of course with two quilts you could make one on the machine and one by hand. Or quilt them completely different ways.
Be sure to find inspiration whenever you need it because as you feel they are treasured now, that will only increase as they come closer to the finished quilts they will someday be.