1. Hang themed group photos in matching frames. Such as travel pictures, kids school pictures, your pet, or a favorite place like a beach or cottage.
You can hang them up side by side or vary the lay out, just keep same distance between frames everywhere.
You can pick up some frames to match your decor. Use same size ones that don't match in color that you find at thrift stores and yard sales. Or go with basic black. These solid pine black ones below from Ebay make a bold statement.
2. Frame a map. Maps are usually large so can easily fill that blank wall for you. Below is a map from one of our family's favorite book series, The Sword of Shannara. They had a promotion one time with maps signed by the map illustrator so I ordered one. I found the frame at a yard sale and hung it on our home office wall.
You could use an old world map, a map with places you've traveled or a map of your favorite place.
3. Hang family art. A picture your child or some other loved one gave you makes great wall art.
A picture our daughter made us. I had it on the fridge for a long time but wanted to make sure it didn't get damaged so framed so it would be covered with glass. (on back of it there is a sweet note she wrote to us)
4. Hang your favorite t-shirt. Have a favorite t-shirt with saying or band you love but you no longer wear it for some reason. Then hang it on your wall. Cut the front of t- shirt off and staple to blank canvas, thick square of styrofoam or wood board.
My daughter grew out of this favorite t-shirt, so I stapled it (on back edge) to one of the canvas rectangles below that I picked up on ebay.
Have done that with a few t-shirts to hang as bedroom wall art. Have also made some small throw pillow covers with some too.
Don't tuck those favorite things away in a box somewhere. Give them a place in your home, and Enjoy them!