The crossword solutions for the term USEFUL FEATURE are 'AMENITY' and 'PLUS'. An AMENITY is a feature of a place or service that makes it more pleasant or convenient. It can refer to a physical feature, such as a park or pool, or a service, such as a concierge or valet. PLUS is a term used to describe something that is an added benefit or advantage. It is often used to describe features of products or services that are not included in the basic package but are available for an additional cost.