Hundreds of great classical music selections, but my favorites are:
Au fond du temple saint (duet) from the Pearl Fishers (Bizet),
Blue Danube Waltz (Strauss II),
Canon in D (Pachelbel)
Dance 1, Jazz Suite 2 (Shostakovich),
Dance of the Furies (Gluck),
Di quella pira (duet) from The Troubador (Verdi),
Fantasie-Impromptu (Chopin),
Farandole from L'Arlesienne (Bizet),
O mio babbino caro from Gianni Schicci (Puccini),
Piano Concerto No. 3, lst Movement (Rachmaninov)
Rondeau (Moret) -- think Masterpiece Theater,
Sarabande from Suite No 11 (Handel),
Symphony No. 4, 2nd Movement theme (Brahms)