I saw this tip somewhere and have used it with great success. Make the sleeve as suggested above but make it about 1" shorter on each side. To hang the wall hanging use a dowel and screw an eye-hook in each of the cut ends of the dowel. You make the dowel the length so that with the eye-hooks screwed in each end the entire length is just shorter than the width of your wall hanging. Use two picture hanger hooks in the wall and slip the eye-hook over them. Your wall hanging will look like it is floating on the wall and it is very economical to make.
The dark blue gets my vote.