What piece of music never fails to make you smile or feel uplifted, and why?

Khachaturian’s masquerade suite - just the most lighthearted music I know

Ravels piano concerto for left hand and Adagio for strings.

Last movement of the Brahms Symphony No. 2

Last movement of the Chopin Sonata in b minor

Last page of the Franck Choral in a minor for organ

How is one to choose, there are so many good ones!

For pure simple joy I'd say Chopin Nocturne Op. 9 No. 2, for cheerfulness and brilliance Chopin Etude Op. 10 No. 5, and to add a few heaping tablespoons of excitement and exhilaration Rachmaninoff's Rhapsody on a Theme of Paganini–to name a few, there are too many others!