24 members currently on BGA - If all agreed to play in a Round Robin tournament - 23 concurrent games would be mind-blowingly epic!
If I'm not mistaken 15 is the maximum number of players in case of a round robin tournament.
The solution could be a two-phase tournament: in the first phase the players would be divided into groups (the size of a group can't be larger than 15), playing round robin within the groups, and then the first x players advance to the 2nd phase of the competition where another round robin tournament can take place. I'm voting for this format. (It is supported by BGA.)