Feuer, who died last year at age 95, produced classic New York musicals like Guys and Dolls and Can-Can and How to Succeed in Business Without Really Trying.

So, in photographs from listing broker Daniela Kunen, a Prudential Douglas Elliman managing director, the apartment looks like the set for a show about old-school uptown affluence: The antique kitchen is almost all white, except for little red chairs and black-and-white deco floors; the chandeliered dining room has ceramic bowls in the shape of lettuce, plus a mirrored wall.

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630 Park Avenue

Best of all, the living room has floral armchairs and herringbone floors and a white-swan statuette in front of the fireplace. “It’s like a little jewel,” said Ms. Kunen.

“I find it ravishing!” said Ms. Schiff. “It’s the most beautiful sitting room in New York—I’m thrilled.”

Were there Broadway mementos? “There was a piano with a lot of sheet music,” said Ms. Kunen, “but no other noticeable paraphernalia. I think the family cleaned out a lot of stuff before I got it.” But the stardust memories live on: Neil Simon, Julie Andrews, Harold Prince and Jimmy Breslin all eulogized Feuer at his memorial service last year.

According to city deeds, Ms. Schiff is downsizing from an apartment four blocks north, at 550 Park Avenue, which she sold earlier this year for $5.3 million. (She probably had the cash for 630 Park’s demand of 50 percent down.) Fashion deity Valentino has said that Ms. Schiff introduced Jackie Kennedy to his couture, which made him famous.

She’ll fit in perfectly: The apartment’s inlaid-marble foyer leads to the two bedrooms, the swan living room and the master bathroom—all facing Park Avenue.