You have nothing to lose and much to gain. The worst thing that could happen is that you might have to repair a few nail holes if you don’t like it.

In a word? No.

It will definitely look and feel cluttered. You also run the risk of photo frames falling off and breaking. Any other photos of your space that may help us recommend for alternative placement?

I understand what the others are saying, and I can appreciate that JandSand have very little display space for photos. How about replacing the pillows on the sofa with some custom photo pillows commemorating their travels.

Can you put the photos in easel frames and set them on top of the ledge?

I can already see that the general consensus is "No". I'm glad I asked -- thanks everyone!

We do have a hallway that could welcome a photo wall, as someone has suggested. I'll go that route instead (my hope is to keep the ledge empty, though it is prone to accumulating clutter...).