Wait, your name is Tom and you chose the handle "John Curtin"? Might I inquire as to why?
I think John Curtin was pretty great, so I stole his name. Are you like my alter ego or something? I have a feeling we shouldn't be interacting because it wil cause a tear in the fabric of the internet or something.
Well, that does seem like a fairly arbitrary category to choose. Why limit it only to the early 20th century? A lot of the music of the early 20th century (Mahler being an obvious example) was more or less the same as that of the late 19th. And it's not like the stylistic landscape changed dramatically at the midpoint of the century, or rather, any more dramatically than at any other time.
All I'm saying is that it'd be pretty odd for your musical taste to coincide exactly and exclusively with early 20th century classical styles. Is there any particular reason you're interested in this period?
It's not that my taste coincides with it, it's that it's an era I'm less familiar with (especially compared to stuff after it) and one that I think I'd still enjoy, so I'd like to learn more about it. Even if some of it sounds like late 19th century music, that's fine... at least I'll have learned that this is the case, and in all likelihood, it'll have been a more advanced and updated form of 19th century music, which would probably appeal to me more.
Oh, I see, thanks for clarifying that. Unfortunately I think I'm in a similar boat to you in that the early 20th century is the period I'm least familiar with as well! So I can't really give a strong list of what's hot and what's not in the early 20th century. I have a feeling that the way Schoenberg was first introduced to me (as "hey kids! Isn't this music just
awful sounding? This is the kind of stuff they invented in the 1910s! So let's play some more Handel concerti grossi!) put me off it. Of course, they did give us Debussy of examples of how 20th century music could be beautiful, but they kind of avoided beauty in atonality and presented it as being wankishly obsessed with internal consistency without worrying about whether it sounded beautiful or not. Which was unfair and missed the point really.
I'm not really helping. Mahler's symphonies are great if you're a fan of the grand German symphonic tradition, but like I said they are more in the 19th century than in the 20th century. But Strauss wrote in a similar style, and he was around until 1948 (Mahler died in 1911), so we can't really call Mahler a 19th century composer just to be tidy, because that is meaningless. Strauss' operas were in the same vain of Wagner, but he employed dissonance more often. This isn't to say that he wrote atonal music; what he did was contrast dissonance with consonance in the same way it had been employed way back to baroque music - to create tension and resolution. The difference being that Strauss' dissonances are harsher.
There's also the English tradition that took off - there hadn't been a major English composer since Purcell in the 18th century. Everyone knows The Planets, but Holst's other music is certainly worth exploring. Most of Elgar's music is good too, I like his 2nd symphony most.
I also agree with all the music that's been suggested by others. I find the early 20th century to be difficult, and a lot of late 20th century music is focused on trying to come to terms with what happened earlier on in the century and get past the difficulties.