I love listening to his piano concertos while I read as well, especially 2 and 3...
and then Mozart's Requiem I can do, I have always loved the mood this music has for any particularly sad or tragic story...
and Abbess Hildegard of Bingen... A Feather on the Breath Of God... There are a couple good versions of this, and I love it for reading... it is so wonderful and relaxing... and immerses you in beauty...
and recently: Oliver Schroer--- Camino... it is so amazing, what he does with a fiddle in this piece.... it is so relaxing, and beautiful... it turns the fiddle into a sad and soft instrument, lonely and forlorn and melancholy, and then joyous at the same time... it is wonderful...