If one of your stays is at the Westin Vendôme, I suggest that you give the full-size chocolate macaron at Ladurée another shot. Their historical patisserie is close by, rue Royale.
Pierre Hermé, that was the Chef Patissier at Ladurée for years, has a location avenue de l'Opera, that is also at a walking distance.
You can suggest the hotel in advance that you would like that as your in-room amenity ;-) .