Postby trutherous » March 31st, 2010 7:17 pm
When both parties are leaving you use the same expression for when the other party is leaving.
안녕히 가세요
You can also add 살펴 가세요 (take care/go with care) just after you say goodbye and this should be quite impressive to a Korean party coming from a non-Korean.
In the specific case of driving you can add 운전 조심해 가세요 (운전 =driving 조심해 =carefully 가세요 =going /drive carefully) which should be equally impressive to your listener.