This is an idea I had for a while and maybe it can be implemented into the game. Like in Final Fantasy IX, with the auction house and other fun mini quests and missions, could we get an arena added as well. In Final Fantasy IX you had a monster that was difficult to beat each cycle, you beat it, you get rewards.

If they could have a solo, 4-player, and 8-player trials to beat with rewards for defeating it(MGP of course, gear, minions, etc.). The resources are there and they could borrow old trial bosses or dungeon bosses and beef them up, as well as introduce Gold Saucer specific trials with unique enemies. I think that will add value to the Gold Saucer, and have players lined up and while waiting for a que it would give them reason to participate in the events and mini games within the Gold Saucer.

With that it could open the door for more events, mini games, etc. that could be added as well.