Born in Miami and raised in Baltimore County, Mr. Day was the eldest of four sons, all of whom followed in their father's footsteps to pursue careers in journalism.
Mr. Day's route through newspapers took him from Philadelphia to Washington, where he covered politics during the turbulent administration of President Richard M. Nixon.
He later spent the bulk of his career at the Times, overseeing its editorial pages.
Mr. Day graduated from City College, then attended Harvard University, majoring in classic literature.
He served in the Army from 1955 to 1957, then landed his first journalism job as a general assignment reporter at the Philadelphia Bulletin. There he met his wife, Lynn, who was also a reporter.
"He had a wonderful smile," said Mrs. Day. "He was such an interesting person. He was curious about everything in life."
Neither Mr. Day nor his brothers intended to follow what would become a family newspaper tradition, said his brother Joseph Day.
"I think it was more by osmosis and respect for our father and the profession rather than a specific prodding," said Joseph Day, who began his career at the Milwaukee Journal Sentinel. "I know for me, I thought, 'Gosh, my father has had an interesting life,' and that was appealing."
They were hesitant to work for The Sun, where their father, Price Day, was an editorial page editor and World War II correspondent.
Price Day was the only reporter from an individual newspaper to witness the surrender of Germany at Reims. In 1949, he won a Pulitzer for a series on India's first year of independence.
"They didn't want to seem like they were riding his coattails," Mrs. Day said.
Yet conversations around the family dinner table and a lifelong curiosity of the world around him influenced Mr. Day to pursue journalism, she said.
"Price was a critical mind, and Tony was just like him," she said. "He was the most honorable person I have ever known in my life. He never compromised on principles."
After three years at the Bulletin, Mr. Day was promoted to cover politics in its Washington bureau and served as its chief in 1969. The same year, the Times offered him a job commanding the editorial board.
Mrs. Day was reluctant to move across country.
"I told him, 'I think Washington, D.C., is a wonderful place to live,'" Mrs. Day said. "And he said, 'To be afraid of Los Angeles is to be afraid of the future.'"
Mr. Day excelled at the Times, and during his tenure the paper published a controversial editorial calling for the end of the war in Vietnam, Mrs. Day said.
"He had lots of opinions, and he had a wonderful run in those years," she said.
Mr. Day was a classical music buff and enjoyed trips to the opera in Santa Fe, N.M., where he and his wife retired. An avid reader into his retirement years, he continued to write book reviews for the Times, including one published last month.
Mr. Day loved literature, especially 19th- and 20th-century history and biography, said his wife.
"It came to a point where we kept adding bookcases," Mrs. Day. "It was wall-to-wall."
He also loved adventure and traveled extensively throughout Latin America. As a board member of the Inter American Press Association, he visited such countries as Mexico, Brazil and Chile. He spent time with friends, including famed author Gabriel Garcia Marquez and former Nicaraguan President Violeta Chamorro.
In addition to his wife and his brother Joseph, he is survived by a son, John Day, of Santa Fe; two other brothers, James Day of Berkeley, Calif., and Thomas Day of Santa Fe; and three grandchildren.