Scanning 20th century music

I haven't read the book reviewed in this article, but I found it intriguing enough that I plan to get and read "The Rest Is Noise" by Alex Ross. And I thought the review itself provides a reasonably good overview of/introduction to 20th century classical (or "serious" or symphonic or whatever) music for someone who is curious but not very familiar with it. Of course you have to hear music to get an appreciation for it, but if you want a guide to what was significant in the 20th century, the classification of Stravinsky, Schoenberg and Bartok as the century's most influential "modernists," with the sometimes really weird Anton Webern as "chief prophet" and John Cage as wild card isn't a bad place to start, though I'd mention Alban Berg as well. As for those who were less musical bombthrowers but significant, Debussy, Shostakovich, Ives and Sibelius, Benjamin Britten and Steve Reich are worthy of consideration, though I find Prokofiev a more appealing Russian than Shostakovich and I have yet to grasp what it is about Steve Reich beyond a certain hypnotic charm. And I'd rank Ravel at least equal with Debussy.