Never thought of Burnett being on television, but you are correct Lansbury might have been a great choice. She was robbed of doing "Mame" in the film version an unforgivable faux pas on the annals of film. Shirley Maclaine might have been a great choice also as Miss Hannigan.
Carol Burnett was excellent as Miss Hannigan, and loved Tim Curry and Bernadette Peters. Would love to have seen Bette Midler as Miss Hanningan she would have been incredible.