He, He! So you want to impress a young lady so that you can have your evil way with her. Oh, that I were young again.
Well let an old man offer some thoughts. Don't set out to impress her by showing off. If she is visiting you she is already interested enough in you as a person. Pay attention to her and her interests and loves in life. Be a good listener and show her that you are attentive and thoughtful. This will make much more of an impression than your ability to play the piano. Most men try to show off in front of the girls but this is not a turn on. Most girls want someone who is thoughtful, kind, attentive, and who has some gentle traits. If you can make her laugh, so much the better.
If you really want to guide the conversation to music then find out her tastes. If it is more popular music then perhaps you could point out that modern pop goes back to the early blues and boogie - genres which expressed the hardship of life (listen to the word of performers like Bessie Smith or Blind Lemmon Jefferson). You could perhaps mention that "Boogie" was an implication for sex. That a boogie-woogie house was a brothel. This then gives an opportunity to demonstrate the relentless beat of boogie.
If she is a relative stranger to classical music then choose something familiar and romantic. I would suggest Liebestraume. Tell her Liszt was a huge attraction the society ladies of his time with many of them throwing themselves at his feet. Give her something to stimulate the imagination, e.g.
Imagine a young couple in love with each other. The opening section suggests a degree of shyness as they come together to hold hands. As their passion increases it leads to a lingering deep kiss (first cadenza). Their passion increses as they embrace (section following first cadenza) until they are wild for each other, culminationg in sexul frenzy (climax section); they reach their climax (second cadenza); to settle in each others arms in "post coital triste" (final section).
Do, of course put this into your own words and imagination and relate it to Liszt and his passion. (Don't be to brazen about your fantasies with her - at least not yet!) Suggest that much music tells an emotional story and it is the imagination of the listener that supplies the story.
I suggest that you play a recording and listen to it together, preferably with your arm around her.
You can then round off by shyly suggesting that you would like to play it on the piano just for her as a token of her beauty.
Hopefully, this should melt her.
Best of luck.
PS Not a good idea to try to seduce her on a first date.
Topic: First date help?