Surprisingly very few bar stools from the mid-century were designed for the home. They were more likely to have been designed for cafes, pubs etc etc. The mid-century example shown is by Erik Buch and originates from Denmark.

Subway tiles are soooo overdone & really date a house now ( not to mention that they remind many people of, well, subways & public toilets strangely enough ). Glass maybe too contemporary but it's so low maintenance & never boring, the colour & pattern choices are endless. Stone is timeless & easy care. It's personal choice really. Trust your instincts, it looks like you've done a great job so far. Would love to see the end result posted here too. Good luck !

First time builder, your home is looking fantastic. Well done to you and the builder. In my opinion, I would have black bar stools. Wood, not metal. Low or no back, not a high back. Your staircase is beautiful, so I would use that as a guide. Wood, not metal. But black wood, not a stained timber, it would clash with your wonderful floors. Also, The black will compliment your fittings in the kitchen.

And what table. I love the 1st chair and was looking at them last week. But they may be too rich in colour for your grey theme. The light colour in the 2nd pic might work. Personally I am not a fan of the grey chairs. Colour is so personal and I tend to warm colours.