in general, japanese rarely say ”さよなら” or ”さようなら”. because it sounds like "farewell" or "good bye forever". so, they usually say ”では、また会いましょう”、 ”では、また”、”じゃ、また”、”またね”、”じゃね”、”また”. means "see you"

We also say "失礼しますsitsurei simasu(lit. Please excuse me)" for formal situations. Or.... "Saraba!" for samurai. lol

I agree with the second respondent, nin187, in which nowadays the term『さようなら』is hardly used in Japanese. The only time when it is used (based on my limited experience in watching Japanese dramas) is when someone wants to break up a well-built relationship with the other, which is deemed very negative. So I would say that you pick up the suggestions given by that respondent, such as「じゃ/では、(また)」, 「じゃね」, etc., or the one given by the third respondent, chihiro_ito, 「失礼します」, when you are in a formal situation, in a high-class formal party, banquet or ceremony, etc. Believe it or not, last time when I visited Japan, I heard a number of people (especially young students) just greeted with "bye-bye" (バイ バイ) instead :)

さようなら sa yo na la