Anything Baroque and Wagner. I do not like listening to Gregorian Chant for pleasure though.
I love Tannhauser Overture.
I am completely in love with Die Meistersinger von Nurnberg:
Here is the Prelude:
and the Finale:
Can you imagine going to a live performance? I hear it is longer than four hours. The Finale really does a good job of "wrapping up" the whole opera in such an epic and romantic fashion.