Possibly my favourite composition is Schubert's Impromptu No. 3 in G-Flat Major. The best interpretation, in my opinion, is by Zimerman, and not by Horowitz:
[ame=http://www.youtube.com/watch?v=KkqDEh-fXVI]Zimerman plays Schubert Impromptu Op. 90 No. 3 - YouTube[/ame]
Obviously I am also heavily partial to French composers from my own area of research in history, but Debussy, Bizet, Lully, Rameau.
Those are celebrated on their own. Satie is sometimes overlooked by musicians outside of piano:
[ame=http://www.youtube.com/watch?v=q7DBoiyBoJ8&feature=related]Erik Satie "Trois Gymnopédies" - YouTube[/ame]
Some well-known, but perhaps not as famous, works include Meditation, which was instrumental (no pun intended) to leading me to appreciate classical music earlier on in life. Again, the best interpretation (a moderate tempo, tone and absolutely beautiful rubato) is, for me, Vengerov's:
[ame=http://www.youtube.com/watch?v=yemjrHeh9gY&feature=related]Maxim Vengerov - Meditation from Thais - YouTube[/ame]
Wagner's Die Meistersingers has long been tarnished by the Nazis, but even Furtwangler's conducting of it (which you can find on YouTube, and which I didn't post simply out of convenience) is amazing.
[ame=http://www.youtube.com/watch?v=pNdLpJILRzs]Richard Wagner / Die Meistersinger Von Nürnberg - Vorspiel zum 1 - Aufzug - YouTube[/ame]