Classical Music has got to be the most relaxing music ever created by man. I love Strauss, Beethoven, and Brahms, but you're right
Might (hey, that rhymes
), I'd give up any of those artists for Howard Shore's score (I can't believe how much I'm rhyming today). Just as Strauss' waltz will take my mind to another place and time so does the Howard Shore.
The Bridge of Khazad-Dum has got to be my favorite soundtrack from the movies. It has enough exciting notes in it to keep your attention through most of the song, with some of the best written music from the movies in it.