The newest poll asks, "Who was the most successful child of an American President who did not become President?"
I have deliberately left off John Quincy Adams and George W. Bush. They both became President in their own right and can be deemed successful regardless of any personal political views. Picking out five from the remaining children was hard. However, I have settled on five.
I have used The Presidents of the United States and their Children to identify five. Text quoted below is from that site:
Charles Frances Adams - "He was born on August 18, 1807. He died of a stroke on November 21, 1886, at the age of 79. The third child of the nation's sixth chief executive might possibly have become the third generation of his family to become president. He was determined to champion causes ahead of their time. He was beloved and respected by his peers. Charles was fluent in several languages, graduated from Harvard at seventeen and apprenticed in law under Daniel Webster. At twenty-two, he married Abigail Brown Brooks, daughter of a wealthy Bostonian. He then turned to promoting the radical position of the abolition of slavery. By 1841 he entered the Massachusetts State legislature. In 1858, Charles was elected to the House of Representatives. During the Civil War, he negotiated behind the scenes, and eventually England stayed her hand. In 1872 and again in 1876, Charles' name was placed in nomination for the presidency. By that time, however, he was leading the charge for civil service reform, another controversial idea years ahead of its time. Some historians, then and now, believe that Charles would have been elected president had he been willing to do what was popular, rather than what was right. "
Robert Todd Lincoln - "He was born August 1, 1843 and he died July 25, 1926. He served as Secretary of War and as Minister to Great Britain. He was an effective president of the Pullman Corporation. Considered by many historians as one of the most successful of presidential children, Robert married Mary Harlan, a Cabinet Secretary's daughter, had three children and lived into his eighties."
James Webb Cook Hayes - "He was born March 20, 1856 and he died July 26, 1934. Known all his life as "Webb, he served as a secretary in his father's White House. He latter launched a successful business career that spanned decades and made him rich. He reorganized one small enterprise, which would grow into the Union Carbide Corporation. He married Mary Otis Miller they had no children. Webb pursued his lifelong love of the military, risking his life as a soldier of fortune around the globe until he died at 78."
Marion Cleveland Dell Amen - "She was born July 7, 1895 and died June 18, 1977. Marion was twice married, first to William Stanley Dell with whom she had a daughter and, after his death, to John Harlan Amen. Marion spent 17 year of her life dedicated to serving the Girl Scouts of America. She served as community relations adviser. Marion's later husband John became famous as a Special Assistant to the U. S. Attorney and served on the U.S. legal staff at the Nuremberg war crimes trials in Germany."
John Kennedy, Jr. - "John Fitzgerald Kennedy, Jr., was the founder and publisher of George magazine. He married elegant, blond Carolyn Bessette on September 21, 1996. John was a lawyer, an assistant district attorney, a Peace Corps volunteer in Guatemala after a severe earthquake, a tutor of underprivileged children, an amateur actor, an athlete, and an American icon. He had no children."
Obviously, other children could have been selected as well. However, I was limited to five and I think they were all successful.