She was celebrated for her salons, where she hosted intellectual and artistic masters including Marcel Proust, Colette, Giovanni Boldini, Maurice Ravel, Isadora Duncan, and Gabriel Fauré.

A number of musical works were premiered at her salons, including excerpts of Claude Debussy's Pelléas et Mélisande and Prélude à l'après-midi d'un faune and Fauré's Mandoline from Cinq mélodies "de Venise".

[3] As a young woman, de Saint-Marceaux was courted by the composer Camille Saint-Saëns, who asked for her hand in marriage, but her family demanded she refuse him due to his rather Bohemian situation.

[2] De Saint-Marceaux became a celebrated salonnière in the 1880s up until the outbreak of World War I, hosting musical and artistic salons at her Malesherbes mansion, where she invited painters, writers, and musicians to mingle with aristocrats and other members of the Parisian upper class.

[6] Her salons were frequented by Colette, Henry Gauthier-Villars, Marcel Proust, Alfred Cortot, Jeanne de Montagnac, Maximilian von Jaunez, Florent Schmitt, Henry Février, Jacques Février, André Messager, Giovanni Boldini, Maurice Ravel, Claude Debussy, Reynaldo Hahn, Gabriel Fauré, Georges Clairin, Charles Koechlin, and Jacques-Émile Blanche.

[1][7] Her salons were described in the correspondence and writings of various attendees including Fauré, Ravel, Schmitt, Koechlin, Messager, Hahn, Cortot, Proust, Colette, and Gauthier-Villars.

She didn't force anyone to listen to the music, but repressed the slightest whisper... No one thought it bad that Monsieur de Saint-Marceaux was absorbed in reading, that the sons of the house retired to the upper floor, that the painters Clairin, Billotte took refuge in a quarrel between painters, whether Gabriel Fauré preferred to music the pleasure of drawing in three strokes of the pen the portrait of long and bearded Koechlin, or that of Henri February, father of Jacques.

Sometimes, the phalanx of musicians threw themselves on old music books, played, sang with soul now Loïsa Puget, plundered a repertoire of 1840 haunted by madmen on the moor, Breton brides leaning on the moles, young girls intoxicated by the waltz … Often, side by side on the bench of one of the pianos, Fauré and Messager improvised with four hands, competing in abrupt modulations, out of tune escapes.

Fauré, emir bistré, shook his silver crest, smiled at the pitfalls and redoubled them… A parodic quadrille, with four hands, where the leivmotives of the Tetralogy met, often rang the curfew.

Frequently in attendance were Édouard Bourdet, Robert de Flers, Abel Hermant, Paul Hervieu, Henri Lavedan, Jules Lemaître, and Victorien Sardou.

She also hosted journalists and critics including André Beaunier, Gaston Calmette, Louis Gillet, Arthur Meyer, and Pierre Lalo.

Ravel, who was a frequent guest of the salon, played private performances of his works for de Saint-Marceaux including Trio avec piano, Ma mère l'Oye, L'heure espagnole, Miroirs, and Sonatine.