Floor tile and Splashback help please

Hi all,
I am new in here but have enjoyed reading others suggestions and responses.

We are about to finalise the details for our new kitchen. It is at one end of a large 12m open plan room.

We have a large bench 5.5 m long along the back of the kitchen and a 3 m island in front.
We have decided on quantum quartz benchtops in alpine white and 2pack poly white drawers throughout.

Our floor tiles are a dark charcoal which blend into a dark carpet for the rest of the space.

I am really unsure about what to do with a splashback. It is such a long expanse I am finding it hard to decide.
When getting our quotes some kitchen designers suggested stone splashback others glass.

I am leaning towards glass but am unsure of what colour I should do. I am thinking of using red accents throughout the space to add some colour but don't really want to do a red splashback.

Any suggestions would be greatly appreciated.

Will the splash run the length of the 5.5m? Only reason I ask is some places have a maximum run of glass should you want it in one piece. Otherwise you may have to have 2-3 pieces over that length.

You have pretty neutral everything else so it really depends on the mood of the room that you are trying to convey. In our case we had such a strong colour (blue) in our stone benchtops that we wanted something to tie in with them. So we ended up deciding on a photo of our favourite beach behind glass.

What other furniture will you be using in the room, how much light, do you want an informal / formal / casual feel?