This Mixcloud should provide you with examples of all of the classical forms: art song (Arthur Sullivan's "The Lost Chord"), cantata (Bach's "Jesus, Joy of Man's Desiring"), oratorio (Handel's "Hallelujah Chorus"), concerto (Bach's "Brandenburg Concerto No. 2 in F, I. Allegro"), symphony (Arvo Part's "Symphony No. 3: First Movement"), fugue (Bach's "Contrapunctus I"), plus an orchestral suite (the awesome "Mars, the Bringer of War" from Holst's The Planets). The only one left out is mass.
