I do not play every server available,
But on my server most dungeons have almost no players who are willing to do them!
Simple solution,
Create a party system that asks you which dungeon you want to do and what path,
The use of this system and completing a dungeon using this system will reward you with gems/other rare items.
So in the party UI there will be a settings button,
You click on this button and it will open up a whole new window.
In this window you can decide what dungeon you want to do and what mode, and/or path.
A party leader can say what professions the group is looking for,
1 Warrior (Toughness)
1 Elementalist (Healing)
1 Ele.. you get the idea.
The reward,
I said Gems earlier but that is a bit too much I gues,
You could make it anything you could possibly make it tokens for the dungeon or any other item which is rewarding both then and in the future.
This system will greatly improve looking for a group for dungeons and should be useable through out Tyria so that you do not have to wait for a dungeon group to assemble at the dungeon gate.
~ Jeff.