Ah, "Fantasia on a Theme by Thomas Tallis", I take it? Vaughan Williams is always good but that is magnificent.
Let's see, I'll go chronologically:
Baroque-era music is beautiful because of the way it invokes sort of feeling of calm mathematical precision. My favorites from this period would probably be J.S. Bach, Vivaldi, Handel, and Corelli, (who often sounds a lot like Vivaldi.) Everything Bach wrote was divine, but I particuarly like his flute sonatas and his choral works. Then there's Handel's Messiah, and all of Vivaldi's concerti and sonatas.
From the Classical peiod, I listen to a lot of Mozart, C.P.E Bach, and Devienne. It's not really my favorite musical era overall, but just about anything by Mozart is divine. His operas are beautiful even for some people who don't particularly like opera.
I can't think of many romantic composers I habitually listen to, so I'll move on to the really good stuff: the 19th and 20th centuries. Here, in my opinion, is where much of the most beautiful music ever written is found, (much of it by French composers.) Debussy is probably my favorite composer of all time. Many of his works are tone poems, taking a specific image, often relating to classical mythology, and describing it with an ethereal, dream-like sound. He wrote "Nuages", which is a nocturne describing clouds moving through the night sky, and it is possibly the most beautiful piece of music ever composed. It has one moment that feels to me to be the perfect musical description of complete wonder. But really anything by Debussy is beautiful. For Ravel, some of the best are "Bolero", "La Valse", and "Lever du jour", which is one of the happiest works in the musical world. Khachaturian has some great ballet suites--"Gayane's Adagio" was used in 2001: A Space Odyssey-- and Ibert wrote one particularly insane flute concerto. I'm also a fan of Orff's "Carmina Burana" and of various things by Ralph Vaughan Williams.
Gah, there's too much to talk about.
