Last night I finished up a few custom request ruffle thongs for a customer. She wanted them in a selection of my fall/winter fabrics. The ruffle thong uses quite a bit of fabric - anyone who has used my pattern will know that they look huge before you ruche them with the elastic - but they are snuggly and comfy for a thong!
I use a pearl edge on my thongs, which I do with my serger. If you don't have a serger, you can easily fold over your edge and zig-zag with a narrow stitch. It finishes it off just as nicely! I've also added narrow stretch elastic to the raw edges before ruching, which creates a nice, lacey ruffled edge.