I have a idea of a new game mode you could introduce that i think would have a great amount of success. I say this because this is a game mode that i have only seen in one other server, a brazilian one and it was pretty big back in the day. But that server as since closed, which is really a shame because my best memories of minecraft come from there. But as the game goes, its a 100 player mega sky wars, where there were 4 teams of 25 and each team had a island of their own where there was a flag made of blocks of wool of the colour of the team, and a big island in the center that was the feast. The goal was to destroy 20 blocks from the opposite team flag and then kill all the team members, that would always respawn while the flag was still "alive". I believe this to be a very dynamic and fun minigame and one i can see making success in your server as it has been previously shown to be successful in other ones. I will add here a link of a video, not mine, of the mini-game for better understanding.
Really hope you take this into consideration, best regards
Really hope you take this into consideration, best regards