I made shopping bags for Christmas gifts a few years ago using this Kwik Sew pattern:
http://sewing.patternreview.com/Patterns/4987. I hope you can see the stitching on the outside of the shopping bag.
It has a technique for reinforcing the vertical seams that also gives the bag some structure. After the bag is completed, sew a line of stitching about 1/8" from the edge from the bottom corner to the top of the bag. I used my edgestitch foot and topstitching thread. It looks very professional and with a plastic insert in the bottom, the bag will stand up on its own. I used cotton home decor fabric that was heavier than quilting fabric.