You could have a recitation of the family history, a few speeches from the family elders, or a fun event like a dance contest. Get everything in place as the event draws near. When the reunion is just a few weeks away, send out a one-page reminder, or call relatives who said they might come. Be sure that all your materials are ready. Mount documents like marriage licenses, high-school diplomas, and maps of the old neighborhood or town.
Old photographs are probably the most popular of all attractions.
Leave room for people to write down information. Family trees are a must. This allowed people to study their branches and make corrections or additions. Have an evaluation sheet at the reunion. This will allow everyone who attends to get in their two cents and tell you what worked and what didn't.