These picture arrangement ideas may helpful!
Stairwell - ledge, frames, books, etc
Benjamin Moore Edgecomb Gray The 3 best not boring paint colours for a dark hallway or stairwell by Kylie M Interiors. E-decor and Color Consulting
staircase photo wall collage - for when we have stairs - like all the black frames.
Paint Palette of grays for a house - great description of each color she used pale oak as wall color and horizon as ceiling color. I like that idea