I always use the 'wine glass' test for placemats and table runners. Would a wine glass be tippy on it? For this reason, I often use the thinnest of batting or just flannel as batting. I often do a birthing method and like to do 2 rows of topstitching. One very close to the edge and one in about an inch. I like to use a decorative stitch for these rows and it creates a very nice 'border' edge. Another option is the self-binding edge in which the backing is 1 1/2" bigger than the front and you fold it over to the front and stitch. (I also like to use this when making baby quilts so the baby can not chew the binding off.)