Just for fun; would be nice to see what different boutiques offer for clients during their shopping experiences - macaroons, cakes, chocolate or nothing!
The same as others have listed above. Though, at Sèvres you can ask for Alain Milliat apple juice, which is my favorite bottled juice brand out there. Sèvres also has a « special » water fountain like machine they use so the water isn’t Evian. Lastly, you can’t go wrong with champagne served in Puiforcat tumblers. I have also had some petits fours and macarons served at the Shanghai Maison years ago when it was my home store.
It's usually water, although one time I remember my SA offering me an orange juice. However, I went in on my birthday last year and she served me champagne.