I adore movie scores. I don't think I have an absolute favorite song, but anything by Thomas Newman, James Newton Howard, John Williams, or Howard Shore are songs I could listen to for hours.
I'm also a fan of classical/instrumental music. Any solo or symphonic piece is worth listening to. :)
"Night on Bald Mountain" By Modest Mussorgsky is one of my favorites. It is also one of my favorite musical pieces in the Disney production called "Fantasia".
I also really like Beethoven's 7th Symphony The second movement, also the "Rite of Spring" and "The Firebird ballet" by Igor Stravinsky and most classical music.
Well, I don't know about favorite, but the other day I heard this rad acapella cover of Dance of the Sugar Plum Fairy. Yes, you're remembering correctly: that song has no words. And yes, you're also correctly remembering the definition of acapella.