Beethoven's Hammerklavier sonata is in some ways, though differently structured, a more mature version of the Moonlight. In the Hammlerklavier, the vigor of the opening allegro finds climax in the cataclysmic fugue of the finale. However, it's the adagio that is the true centerpiece of the work: A 17-minute monologue best described as a 'mausoleum for human sorrow'. At forty minutes long the sonata is a high point in Western art. I recommend the Kempff 1951 performance.
Here is a performance of Wilhelm Kempff playing the famous first movement of Beethoven's Moonlight sonata. http://youtube.com/watch?v=O6txOvK-mAk
Kempff is my favorite Beethoven pianist because he does not attempt to Romanticize the composer any more than is evident in what is written. Here he is relatively old and he even hits several wrong notes in the third movement of the work. However, his feel is sublime and for that, this performance of the 1st movement is one of the best I have heard.