Hey Allum,
As I think about it, these are some of the factors:

1. Desire: The desire of family members to have a reunion, and a number of family members being interested in their roots.

2. Advanced planning: Starting at least a year in advance coupled with great planning committees. Get DEPENDABLE people on your committee.

3. Variety: moving the reunions to new locations. Being stuck in one place has not worked well for us.

4. Effective communication: Utilizing nicely-designed web-page (a great enticer), family yahoo group, mailings, etc.

5. Timing: Having the reunion every other year versus every year.

6. Costs: Keeping the costs reasonable.

7. Word of mouth: if a reunion is well-planned and well-attended, word gets back to other family members who start to attend as well.

8. Harmony: Little to no major disagreements have arisen to date. Confusions, arguments, money mismanagement, etc. can suck the "life" out of reunions as well.

Mel