Changes needed for the melodic and harmonic versions of the scale are written in with accidentals as necessary. The D-flat harmonic major and melodic major scales are:
In music for the harp, D-flat major is preferred enharmonically not only because harp strings are more resonant in the flat position and the key has fewer accidentals, but also because modulation to the dominant key is easier (by putting the G pedal in the natural position, whereas there is no double-sharp position in which to put the F pedal for G-sharp major).
The flattened pitches of D-flat major correspond to the black keys of the piano, and there is much significant piano music written in this key. Pyotr Ilyich Tchaikovsky's Piano Concerto No. 1 is written in B-flat minor, but the famous opening theme is in D-flat major. Tchaikovsky composed the second movement of Piano Concerto No. 1 also in D-flat. Sergei Rachmaninoff composed the famous 18th variation of his Rhapsody on a Theme of Paganini in this key, perhaps emphasizing the generally held view that D-flat major is the most romantically flavored of the major keys; and his friend Nikolai Medtner similarly chose it for the sensually romantic "big tune" in the last movement of his Piano Concerto No. 3 ("Ballade"). Claude Debussy also composed the famous "Clair de lune" in this key, with a significant section in C-sharp minor. Edvard Grieg composed the second movement of his Piano Concerto in D-flat. Frédéric Chopin's Nocturne in D-flat, Op. 27 and Berceuse, Op. 57 are in this key. Franz Liszt composed heavily in this key, with his most recognizable piece being the third movement of his piano composition Trois études de concert, dubbed "Un sospiro". Liszt took advantage of the piano's configuration of the key and used it to create an arpeggiating melody using alternating hands. Several of his Consolations are also written in this key.
↑Charles-Marie Widor, Manual of Practical Instrumentation translated by Edward Suddard, Revised edition. London: Joseph Williams. (1946) Reprinted Mineola, New York: Dover (2005): 11. "No key suits it [the flute] better than D-flat [major]."