For a simple, lightweight, and effective way to display images dry-mount them on a foam core mounting board. Use black foam core so the edges of the board will be black. Add wood stretchers on the back to prevent warping. The stretchers also space the prints about ½" from the wall.
These stretchers are a bit fancy but you can do the same job with 1x1 lumber. To attach the stretchers to the board 3M High Tack ATG Adhesive Transfer Tape #969 is recommended. The following display is from my Seaside series.