Learn French: Bon voyage, Madame ! À bientôt ! - Have a good trip, madam! See you soon!

In English, we say 'Have a good trip.' But in French, for common well-wishes, the 'a' (un or une) is left out. You just say bon voyage, exactly like you say bon appétit or bonne chance (good luck).

How do I know whether to use bon or bien here?

Bon means 'good' and is used to describe nouns (things, people, or places). Since voyage (trip) is a noun, you use bon. Bien generally means 'well' and is used with verbs to describe how an action is done.

Is it normal to say Madame without the person's last name?

Yes, absolutely! In French, it is very polite and common to address someone simply as Madame or Monsieur, whether you know them or not. It sounds much more natural in everyday French than 'Madam' or 'Sir' does in everyday English.

How does À bientôt translate to 'See you soon'?

Bientôt simply means 'soon'. In French, putting à (which usually means 'to' or 'at') before a time word is the standard way to say 'see you'. For example, à demain means 'see you tomorrow', and à bientôt means 'see you soon'.