In chamber music, A major is used a lot. Johannes Brahms, César Franck, and Gabriel Fauré wrote violin sonatas in A major. Peter Cropper said that A major "is the fullest sounding key for the violin.", when he was talking about Beethoven's Kreutzer Sonata.[2]
According to Christian Friedrich Daniel Schubart, A major is a key that is good for "declarations of innocent love, ... hope of seeing one's beloved again when parting; youthful cheerfulness and trust in God."[3]
When music for orchestra is in A major, the timpani are normally set to A and E a fifth apart. In most other keys, they are set a fourth apart.
↑Mark Anson-Cartwright, "Chromatic Features of E♭-Major Works of the Classical Period" Music Theory Spectrum22 2 (2000): 178
↑Peter Cropper "Beethoven's Violin Sonata in A major, Op.47 'Kreutzer': First Movement" The Strad March 2009, p. 64
↑Rita Steblin: A History of Key Characteristics in the Eighteenth and Early Nineteenth Centuries (Rochester, University of Rochester Press: 1996) p. 123
Colin Lawson, Mozart: Clarinet Concerto, A Cambridge Music Handbook, Cambridge University Press, 1996.