Holland America Line attracts scores of devoted fans who love the grown-up-focused experience on board. Entertainment centers on what a mainstream, slightly older crowd would enjoy: The line has hosted “Dancing With the Stars” celebrities and musicians straight from B.B. King’s nightclub in Memphis, Tennessee, and a partnership with Manhattan’s Lincoln Center brings classical musicians on board the line’s Koningsdam ship. Passengers appreciate the little extras, too, from complimentary hot appetizers during the very much observed pre-dinner cocktail hour — at bars all over the ship — to free tote bags for all passengers. Read our full line review.