I think something like this at the top of the stairs maybe one picture at the bottom and then do your gallery wall of family photos in the hall leading to the bedrooms. Sorry never a big lover of family photos in more public spaces . You have a very contemporay light fixture so IMO it can stand alone for decor maybe an interesting wall hanging piece on thta bottom wall.

No photos it’s beautiful as is

I also agree: no photos, it would look too busy. Your staircase and wall are lovely. In your case: “less is more”.

I like the focus on the light fixture by itself.

I think you could do it, but would have to be very careful. The example you show is way too much and also has too much crowded around the light switches. I'd use coordinated frames as in your example, but more space between the pictures. With small pictures, they should be more or less eye level as you go up the stairs.

If your concern is the big blank space above the molding running across the middle, small pictures won't work above there because it's too high up. A possibility might be to skip the pictures and get a large, modern-themed tapestry or wall hanging. It could hang over the molding and would also bring in some color. The pictures could then be relegated to the upstairs hallway as others have suggested.

Takes a lot of effort and $$$ to make these galleries look good.

And in the end, it is difficult to see and appreciate the photos — they become a blur on the wall as one goes up and down daily. They’re too small to see clearly when standing in the foyer.

And then, there is DUSTING. Uggh. Just think about trying to keep the rails and frames in the photo above from collecting the dust that naturally drifts up the staircase. Better to spend your time and money on a huge artwor you can dust with a extender pole without toppling it over. There are a lot of sites where you can order custom sized prints for reasonable cost.

Exactly: one masterfully epic artwork > 50 "blend-in" smaller pictures!

IMO, going for the quantity route is an obvious way to keep with the trends, and it always looks rather forced to me (like someone likes playing tetris too much and decided to try those skills IRL...)

I would surely do a gallery wall. It is your home and you want to show off your family, pets, places you have been etc. I would however keep it simple. For instance oversized, poster sized images. Not a whole bunch of small images. Making sure the frames are neutral to your walls or no frames at all.

You could let the wall trim be the termination point for your gallery and perhaps hang a large piece of artwork above it.

Hi Tee, I love how this staircase turned out. I love the light you chose and the paneling.

Tee, put your pictures of your staircase in a PowerPoint file and start drawing rectangles until you get a design you like for a gallery wall. Give some black frames and some white or wood or other colors you want. 

I remember you wanted the moulding and a great light fixture because you thought the staircase was too bland. You started with nothing.  If you want a gallery wall of pictures, can't you always remove that one strip on the sidewalk? 

However, as I look at the staircase head on, I would not like a bunch of picture frames on the side. Besides, it's not like you have a huge collection after the fire. Have you thought of a single wall tapestry? That soft art could hang over the one piece of moulding. I'm thinking of something silky or with bits of reflective pieces sewn in.

https://www.1stdibs.com/furniture/rugs-carpets/indian-rugs/eco-friendly-distressed-wool-silk-abstract-contemporary-runner-rug-stock/id-f_22396572/

Its your home so you can do a whatever makes you happy. But the architecture of your home is visually beautiful full design it will look cluttered if you add anything IMO. I would find another place for the pictures

Rehabit, Tee lost everything in a fire, and the crown moulding, staircase, and light fixture are all her design. Isn't it amazing what she's done?

Tee, can you show us what you decided on? It would help us as you ask for help in other spaces.