I just got this, and am still warming up to it:
I think you'll like it, if you don't have it already.
I'm also a huge fan of the Bartok concerti, which you probably already have, and although close, but not from, the 20th century, the Saint Saens concerti; current favorite recording of the Saint Saens is the complete concerti on Hyperion with Stephen Hough and the Birmingham Symphony Orchestra.