An Alan Hovhaness mailing list has pointed out a site by musicologist/critic Walter Simmons dedicated to:
The discovery and dissemination of 20th-century classical music that embodies traditional aesthetic values of beauty, clarity, and emotional expression.
For example, his reviews from Fanfare magazine are available, including a review of the Trio Phoenix recording of Henry Cowell's Set of Five ("an ingratiating musical stew"). The review also mentions the New Albion CD by the Abel-Steinberg-Winant trio, which I would recommend.
And following the connections, William Winant is the percussionist who worked with Sonic Youth on their Goodbye 20th Century CD I like so much (and that might not match traditional aesthetic values). In any case, I look forward to perusing his site as it champions 20th century classical music.