hmmmm.....something to show off with. Well, heres ones that worked for ME in the past.......
Liszt, the 2nd Hungarian Rhapsody (though they're all good), the Sonata, Mephisto Waltz, Dante Sonata and Rigoletto paraphrase
Chopin, any of the Scherzos, Ballades nos. 1 and 2, the Fantaisie in F min, the big waltzes, the fast etudes (op. 25 no. 12 proved very effective for me...)
Alkan, Festin d'Aesop (but thats one HELL of a pregnant dog of a piece)
Or anything I've missed that Kissin plays for an encore.
AD