I would find some fabulous wallpaper and forget about hanging any decor there.

On all 4 walls you think?

You have 3 postings of the same dilemma.

Why do you have two posts about the same issue? It will be confusing since you will receive comments on both.

I commented on the other one - I asked if you really needed a door vs. just a doorway opening leading to your living room/hallway? It seems odd to have a door there also.

All walls or just one? Depends on which you prefer and what kind of paper you choose. One wall of colorful and busy pattern will make it more like a replacement for artwork, all 3 will make it a statement foyer, again depending on the pattern.

The mirror should be centered exactly on the chandelier. The chandelier and the little oval mirror go together quite nicely. Are there two mirrors? I see a porion of one it looks like on another wall? What is the space with the G above it? Pls take a picture from there so we can see the whole hallway, thanks.