Her main Broadway credit was choreographing the Tony Award-winning original production of Big River.
She worked extensively Off-Broadway from the mid 1980s to the mid 2000s. Among her primary credits are the 2006 revival of The Fantasticks, which is still running, plus Fermat's Last Tango, Noel and Gertie, and the 1984 revival of Pacific Overtures.
She choreographed several shows by her husband, Fantasticks lyricist-librettist Tom Jones, and his partner Harvey Schmidt, including Mirette, Philemon, In the Bone Room, Portfolio Revue, The Show Goes On and the 1996 revival of I Do! I Do!
Ms. Watson was born in Tulsa, OK to a family "very active in dancing and singing," Jones told Playbill.com. She came to New York in the early 1960s after her older sister, Susan Watson, had her first big success as the original Kim MacAfee in Bye Bye Birdie. Susan late, who had originated the role of The Girl in the summer 1959 one-act version of The Fantasticks, later starred on Broadway in No No Nanette.
Janet studied at the University of Colorado and danced with the Merce Cunningham Dance Company. She became head of the dance department at Texas Tech for a time, and also worked extensively at the Actors Theatre of Louisville in the late 1960s and early 1970s.
She returned to New York in the mid 1970s to pursue a career as a choreographer.
Jones said his wife was "an incredible athlete" who was a competitive diver, a skater, and a regular competitor in the New York Marathon.
But in her professional life, Jones said, her special magic was the ability "to an actor who was maybe insecure and shy about movement, and make them truly believe they could move. That was her biggest gift."
She is also survived by their sons, Sam and Mike.
A private memorial is being planned.