I believe that a gratuity to a particular concierge who was especially helpful is appropriate. When my DW and I stayed at WL in May, we gave a gratuity to one of the concierge staff who went way above and beyond the call of duty to help us during our vacation. He provided a lot of extra service that helped make our stay very magical. When we got back to Chicago, we sent him a special "Chicago" magnet because we knew he collected magnets.