In 1952 Merrill, Björling, and Victoria de los Ángeles made a widely admired RCA Victor recording of Puccini's La bohème, conducted by Sir Thomas Beecham. In 1953, Merrill, Björling, de los Angeles and Zinka Milanov recorded the complete Pagliacci and Cavalleria rusticana.
Merrill was married briefly to soprano Roberta Peters in 1952. They parted amicably; he had two children, a son David and a daughter Lizanne, with his second wife, Marion (d. March 20, 2010), née Machno, a pianist. Merrill liked to play golf and was a member of the Westchester Country Club in Rye, New York, for many years.