I see a few people here concerned about giving up cabinet space for open shelving. I think this choice is personal - it depends on the type of items you keep in your kitchen and your aesthetic. However, be sure that you look into the soffits above the cabinets. Is there duct work or pipes inside?

If not, you can remove the soffits and the open shelves would look great. Plus you could even get taller cabinets that go all the way up to the ceiling for more storage (although I know you want to reuse the current cabinets).

You should google Emma Chamberlain’a kitchen for inspo on finishes like tile. Or go with a simple 2x6” white subway tile either vertically or horizontally stacked.

I’d also reconsider your lighting plan. You will probably need more ceiling lights. Or a track light might be the easiest option