Early on in the selection process I thought about the Pathetique as my Beethoven Sonata as I had already learnt it, but my music teacher's advice was that, as it was so well known, it is a lot easier for examiners to notice errors and therefore best avoided. I might go back and see if I can apply my improved discipline to it.
Stamina is important. As much mental as physical, I have problems by the end (the two Poulenc novelettes) in maintaining sufficient concentration.