Do you have any photos of the room? What style & colour of units and worktop? The glass will look great with more modern, slab styles; the marble may work better with shaker units. There are so many marble-style splashbacks, though, and some are quite heavily patterned and stark. Softer, whiter marble-effect quartzes can look stunning - especially if the worktop matches!

I had a friend with a real marble table……. It had so many layers of protective seals that it no longer looked like marble. But there are alternatives that are better than marble but with the right look. Personally I like ceramic/ porcelain tables. Italians make some of the best porcelain. Although a shade more expensive than plain marble, porcelains have the pattern printed on them meaning you can get a table that realistically looks like a very expensive heavily veined marble without the price tag of the real thing. Furthermore they have great stain and scratch resistance.

I think the marble will look great. Your bathroom fittings and fixtures and quite traditional and marble is an absolute classic so I would absolutely use them if you have enough.

As others have said - please don’t use lemon juice or anything acidic. We have a vanity unit in the family bathroom with a marble top - it has lots of water marks despite it being sealed, and now it’s badly etched due to various cleaning attempts. I have no answers sadly. (We now use specific marble cleaner, but we still get more water marks due to oblivious and annoying teenagers / young adults leaving puddles everywhere).