Bach-Busoni - Chaconne
Early Scriabin sonatas #1 through #4. Also the Fantasy Op. 28
Medtner - His works are fabulous. Forgotten Melodies cycles Op 38, 39, and 40. Sonatas - I'm sure you'll find something "big" in there. "Night Wind" is the meatiest of the bunch, although probably not the best to start with if you haven't done Medtner before.
Have you checked out Chopin Rondo Op. 16?