During her 24-year-long career with the company, Chookasian sang many principal contralto roles and a number of secondary parts. Her roles included Adalgisa, Amneris in "Aida", Auntie in "Peter Grimes", Azucena, Death in "Le Rossignol", Erda in "Das Rheingold" and "Siegfried", Filippyevna in "Eugene Onegin", the First Norn in "Götterdämmerung", Frugola in "Il tabarro", Geneviève in "Pelléas et Mélisande", Gertrud in "Hansel and Gretel", the Grandmother in "Jenůfa", Leocadia Begbick in "Rise and Fall of the City of Mahagonny", Madelon in "Andrea Chénier", Mamma Lucia in "Cavalleria Rusticana", Marthe in "Faust", Mary in "Der Fliegende Holländer", Mistress Quickly in "Falstaff", the Nurse in "Boris Godunov", the Princess in "Suor Angelica", Teresa in "La Sonnambula", Ulrica in "Un ballo in maschera", the Witch in "Hansel and Gretel", and Zita in "Gianni Schicchi" among others. She also notably sang the role of Maharanee in the United States premiere of Gian Carlo Menotti's "The Last Savage" in a cast that included George London, Nicolai Gedda, Roberta Peters and Teresa Stratas.