Since Superman Returns has hit theaters, let me take
this opportunity to recommend Michael Daugherty's fun and engaging
Metropolis Symphony. Unlike most contemporary
compositions, it's as accessible as Beethoven or Brahms; I once
heard Daugherty explain that, having been educated in composition
in the 1970s, when melodic music was frowned upon, he had to draw
on his experience in a rock band to learn how to write melodies.
(The one negative review on the Amazon page should be read as a
positive review in disguise -- the reviewer speaks highly of the
coterie of "legitimate" atonal composers who spent the second half
of the 20th century systematically alienating classical music from
its audience.)