Other D Flats
D Flat is primarily a Romantic invention. Chopin, Liszt, Schumann, and Debussy, are the major perpetrators of D Flat. Bach, Mozart, Beethoven and Haydn generally never wrote in it. Modern composers have tended towards androgynous tonal structures or harsh sharps.
Many of the great and memorable moments in music are in D Flat: Grieg wrote the middle movement of his piano concerto in it, and you can tell. No more pastoral moment exists. Tchaikovsky's B Flat Minor piano concerto has a similarly gorgeous bucolic middle movement in D Flat. The first movement's theme is also in it. Rachmaninoff's most brilliant variation, the 18th, from his Rhapsody on a Theme of Paganini is in it. The third movement, the "funeral march" midsection of Chopin's B Flat minor Second Sonata, is in it, Calla lilies brought to the funeral along with serene D Flat resurrection from the B Flat Minor dead.
Debussy's 9th Prelude of Book 1 and the 3rd and 4th Preludes of Book 2 are ethereal and violent examples of D Flat's psychological range. His Reflets dans l'eau (Water Reflections) from Book 1 of the Images is as filled with water imagery as Liszt's similar Les jeux d'eaux à la Villa d'Este, itself a gorgeous piece in F Sharp, sparkling with rippling sharps, as splashy and frothing in its own key as Debussy's D Flat ponds are water-lilied and Giverny'd. Debussy's Etude No. 2 in thirds (Pour les Tierces, or For the Thirds), was written with Chopin's D Flat Etude for Sixths in mind; Debussy's etude suggests the rolling sea of his opera Pelléas et Mélisande, as well as the water imagery in Clair de Lune, which he was revising as he was composing Pour les Tierces by the sea at Tourville in 1905.
Many pieces have fleeting sections of D Flat. Schubert, in his A Flat Impromptu and in his C Sharp Minor Musical Moment, breaks memorably into it in the midsections. Liszt's First Ballade has sections in it, as does his Rigoletto Paraphrase. In Faure's Opus 37 Nocturnes, the 5th slips into it, as does the 7th. The 6th and 8th are written in it. Debussy's Masques has a section in it.
Four sections of Schumann's Fantasiestücke are in it (Des Abends (Evening), Warum (Why), Grillen (Whims), the midsection of Traumes-Wirren (Dream Visions)), as well as the third section of his Nachtstücke and two sections of his Noveletten. Note the ruminative and soft lighting of these moments, like clouds over cow fields, like a dream sequence in a bad movie.
Liszt's Berceuse (second version) imitates Chopin's Berceuse and achieves some beatific moments despite a dated salonish theme. He also wrote a schlocky Ave Maria in D Flat which makes one mourn the pious price Liszt had to pay for his piece of mind, much in the same way one grieves the loss of Shaw's sociability to socialism.
Liszt's fourth and last Soirées de Vienne, a valse-caprice modeled after Schubert, is in D Flat.
Certain pieces manage to twist gentle D Flat into more exuberant aberrant dioramas, such as Rachmaninoff's 13th Prelude of Opus 32, Liszt's 6th Hungarian Rhapsody, Moszkowski's 12th Virtuoso Etude, Chopin's 20th and 26th Etudes, his "minute" Waltz, and his Opus 70: No. 3 Waltz.