One thing I do when I'm trying to decide these things is to give myself as much visualization as possible...so in your case I'd take that photo and overlay a cut to fit piece of paper with a proportional design of diagonally-laid tile over the floor area and see what I think. Like a very low-tech photoshop :)

I need that kind of literalness to make me comfortable with my decision--visualizing is fine, but this always takes it an extra step and confirms or sends me back to the drawing board.

I have a bathroom which is long and narrow. I did a diagonal with 13 inch tiles. It makes the bathroom look wider and shorter.

My shower has a framless door. I used the same tile on the wall straight up to eye level. Above this there is a 4 inch accent tile, above which the direction of the tile is changed to diagonal.

If you have the tile then do a dry fit over the area and look at it for a day.

Tile on the diagonal in that space will visually eliminate some of the excess linearity that you're now suffering from.

Any time you have an excess of any type of linearity, you can bring things back into scale by changing the pattern.

Same when things are too random. I had friends call me over, they bought a house that had a huge stone patio made from irregular flagstones. It was sort of visually disconcerting sitting on it.

It was overwhelmingly non-linear, and the non-linearity of it was further emphasized by a contrasting grout color. A slight modification to the pattern really brought things into balance.

In a room like that, I generally like the "Running Bond" design....AKA "Brick Lay."

I did diagonal in my narrow bathroom and I like it a lot.

I never knew how much I likes diagonal until we did our master with that pattern. Unfortunately it was our last bathroom, and I now look at all the straight tile and wish it was diagonal.

Try the layout first- excellent suggestion.