I recently sewed up an unlined "housecoat" - a lightweight robe for summer/warmer climates.  Because I used a fabric that is inclined to unravel, I finished all the seams so there were no raw edges exposed.  The seams were sewn as "flat-fell".  I sewed right sides together, trimmed one seam allowance, and turned & stitched the other raw edge under to cover the trimmed.  The raw edges of the facings were covered with a bias binding and the neckline/front edge seam was topstitched to seal the raw edges.