If you are using a duvet to cover a down comforter I would suggest buying a size larger comforter than your duvet. I had the same problem with my sheets, most are made extra deep to compensate pillow top mattresses and the memory foam toppers, so my sheets were saggy!
Also the ribbon idea sounds awesome! my current duvet has ribbon attached to the corners so I just scrunch my comforter and tie it in but I think Ill go back and add them to the comforter corners! maybe one to each side to! |