I'd stick with just one wall, as there's the possibility of making an already narrow hall feel downright claustrophobic!

Personally I don't think that's a wall for a gallery. No one will ever look at the pictures and pictures will close in the walls. I can see using a select few on the far wall which will help diminish the length of the hall..

Hi, a mirror would be good in your hallway and will help adding some light.

Adivra, do you mean the putting some up at the end of the hallway where the light switch is?

Yes, that's what I was thinking. I know it's not a big area, but it could be fun if you selected frames in which you could change out the pictures when you want. That would make it intresting for guests too. Whatever you do keep the frames/mats consistent as in the inspiration photo. You could even put in picture lighting (for a splurge) which would also blow out the wall a bit.