Mission farewell and homecoming
Young men are commanded by a prophet to serve missions when they turn 19. Young Women have that oppurtunity if they are not married when they turn 21. Upon retirement if health permits couples are encouraged to serve missions as well.
A tradition has been for the missionary when he departs and when he returns to speak to the congregation. With special musical numbers and members of the family speaking. Often it sounds like a funeral for a living person. Many times the missionary basically ran the program.
Though in the church handbook and before it was counseled that the sacrament meeting belongs to the bishopric and not to turn it over. A common tradition also is to have a big dinner at a person's home or if that's not big enough the park or school or other public building.
In many lds communities the picture of the missionary appears in the paper as well. In the October 2002 General Conference however Gordon B Hinckley said missionaries are the only ones that get that kind of honor on a calling General Authorities and bishops don't get that honor.
A problem was some wards all they had were mission coming and goings nothing else could get talked about such as high council meetings and testimony meetings. He said if two or more missionaries were coming or going they may speak in sacrament meeting. But families wouldn't and there would be no more special musical numbers. It still occasionally happens though.
And family gatherings were ok but not to have elaborate open houses. Missionary work is still a commandment and important. But farewell and homecoming the technical term any has been removed and it is to be another sacrament meeting.