Maybe (when theres a lil bigger community), we could make a sort of teamwork event. Examples:
Example have 2-3 full parties (with 3 or 2 event GM's as hosters), where 1 GM is the leader of 1 party.
Have the players make a party of 7 people and then invite the GM and make him leader, only first 2-3 parties to get 7 members and invite a GM to the party get to join.
When the parties are ready get the GM to summon his/her own party to a ''private'' map, like CW cage or siege arena or some other place like that. 1 party per 1 map. Tell the players to wait in a corner and tell them not to attack the mobs etc.
Then you just guild speak with the other GM's and decide a amount of mobs your going to make, (for example a 100 Risen warriors and 100 asuras and a Drakul/Kheldor/General Razgul/Animus small mobs, ant,scorpion,rat etc.)
and others of your choose. You can also update them with info on how the other parties are doing to cheer them up or get them to kill faster if they dont wanna loose
When all the GM's are ready, tell the players to kill all the mobs before the other parties.
The party who kills all the mobs first, wins! (a very fun and sometimes long event, if you make many mobs).
And you propably wont even need consolation prizes since the bosses are propably going to drop something
When the player amounts go over 100+ or more you can make 2 parties (one with GM) in the same area or just make more parties to get more joiners.
Another event could be sort of like the one you described, except as teams (also more people can join this than the above).
Tell players they can make this in parties (2-7 member parties, you go hide before that).
The party of 2-7 who get all the quest items (make a huge quest item list since they can do it with 7 players), have to find the GM (all of the members).
Then invite him to the party as a member and then show him all the QI's (they can for example give all QI's PT leader and then show all of them to the GM). First party to get the QI's and find the GM win.
This can be changed though, to be easier to execute (for example allow only parties of 6 and 7 to join to actually make them find 6-7 members, which will already lower the amount of joiners by alot).
A fun event since they actually have to trust in other members to get the QI's quickly to win and also getting all the members to the GM can be fun since they have to guide the other pt members there