The guests at this hotel felt they were well-served by the attentive staff.

well-served 是由副词 well（好地）和动词 serve（服务）的过去分词 served 组成的复合形容词。well 表示"很好地"，served 表示"被服务"。 well-served 合起来表示"得到良好服务的"，形容客人受到周到细致的服务体验。