She hosted a half-hour celebrity gossip show in New York City, on WABC-Radio, called Maggi's Magazine, starting in late fall 1953 and continuing on locally for several years in the 1950s.

[5] Touted as a famous radio and television star (and often as "best-dressed"), she was seen in many print testimonial ads in the 1940s and 1950s, for such varied sponsors as Tintair Hair Coloring,[6] Blatz Beer,[7] and Cafe DeLaPaix.

[8] She hosted a short-lived variety show, Crystal Room, broadcast weekly on the ABC network from August 15, 1948, through September 12, 1948.

The show then moved to ABC, premiering there in August 1951, and continuing through February 1952, shown on Friday nights in the 7:30–8 PM (EST) timeslot.

McNellis, as Mrs. Clyde Newhouse, maintained an active high-society social life throughout the 1960s, 1970s and 1980s, as a hostess of charity fashion shows and as chairwoman of society balls.

She was active in fundraising for the Southampton Hospital, the Parrish Art Museum, Guideposts for Children, the Police Athletic League, and United Cerebral Palsy of New York.