not a fan of the 'curb'

it's a lazy fix for the countertop installers... covers the gap when they don't do a clean professional job. Make a statement and tile the wall.

I agree with your friend adding tile to all three sides is dated. A full wall of tile would be such a focal point!

If nothing else do something more chosen than 4”. 6” at least looks intentional. I have 12” (wall hung faucets) and on back wall only.

Thank you all for the feedback. Sadly the backsplash from the supplier only comes in a 4" and we are not going to tile the wall, but they are all great suggestions.

4” will be fine, just use a tall mirror.

I'd tile the whole back wall...only. 4" tile backsplash IS dated...your friend is right. Love the set up you've chosen...a tiled wall will be nice!