The Wedding March by Mendelssohn
The Nocturne, but there may be some strolling I'm talking about Chopin
The Dream Wedding by Richard
And there are a number of Mendelssohn's songs that would be good to dance to
The Round Dance: The Blue Danube
March of Melancholy
Little Sour Plum Fruit
A Night Outside Moscow
March in A-flat Major
Lots and lots of them
I don't have the sheet music with me, but I think a lot of them would be good to play, either festive, intense, or gentle, depending on what kind of dancing style the owner prefers.