goodnight is "bonne nuit" in France.
Well, I'm a girl, and I would say that some of the best ways to say goodnight to girl depends whether you're saying it to her or texting/messanging her. If messenging her, then don't say it too late, and if saying it to her, then a simple goodnight is all it takes.
Buenas Noches
Buenas noches, guapo.
Que tengas una buena noche.
In Berber, you can say "tanemirt" to say goodnight.
You can say "lafi" to say goodnight in Mandinka.
goodnight
goodnight!
"Goodnight".
In Fulani, you can say "Jaama wolof" to say goodnight.
In Pangasinan, you can say "napagtolak" to mean goodnight.
"You can say "Tek heart" in Jamaican to mean "be happy" or "take heart."
In British English, you can say "goodnight" or "night" as a shorter version.
shab bekheyr
In Polish, you say "dobranoc" to wish someone goodnight.
In Sondhi, you can say "ດີ່ນກັນ" (dien kan) to say goodnight.