추석 잘 보내세요 is probably the simplest, most common and casual greeting. Nowadays people don't use the old-fashioned greetings much, but you can have some variations on the simple ones. * 올해도 또 추석이네요. 편안히 맛있는 것 많이 드시며 보내시길 바라요. Another Chuseok has come around. I hope you relax and enjoy good food on the holidays. * 또 추석이 돌아왔네요. 못 보고 지내던 가족 친척들과 함께 즐거운 시간 가지세요. (for people with a big extended family) It's Chuseok again. I wish you a pleasant time in the company of relatives who join you for the occasion. * 추석을 맞이해서 근심은 모두 떨쳐버리시고 가족과 음식 가운데서 편안히 지내시길 바라요. On this Chuseok, I hope you dispel all worries and have a cozy time surrounded by family and good food. As for "please enjoy the xxx (name of the gift)", we don't say 즐기세요(enjoy) much. Depending on what type of gift it is, you can say it in different ways: - (food) 보내드린 떡[생선, 고기, 술]도 많이 드세요: Enjoy the rice cake[fish products, choice meats, wines] I sent you. - (other things) XX를 보내드리는데 마음에 드시면 좋겠네요: I hope you like the XX I sent you.