Imagine if you will instead of quing up for your  dungeon with your pre-made party and standing around waiting for  something to happen you were able to enter your parties "camp" a Unique  instance somewhat like housing but it would be just a area infront of  the dungeon in question. Any part member is free to enter/leave the camp  and for the duration of the Instanced content all Camp effects will  remain "None of these camp effects would take place in the open world  and only be available within the instance. This camp system could be  made to work with the Duty finder as well cross realm depending on  implimentation but as this generally focuses on dungeons with more  complex and demanding mechanics I will be focusing it soly on Pre-made  groups.
Upon entering the camp you character will be seated at a  campfire doing some mundane animation (Pacing, preparing a pot of food,  checking out his gear for wear, whatnot) and you were then presented  with a menu with a list of option it would look somewhat like this.
- Party Makeup
- Shared Inventory items (Another system I may touch on afterwards)
- Limit Break selection (Another system)
- Provisions (Another sub-system perhaps part of shared inventory?)
- Lore
- Bestiary
- memoirs (Contains your information for this dungeon (How many times run, beaten, time, whatnot)
- Feast (Another system)
Let me touch on these menu options a little bit.
Party Makeup
As  simple as it sounds, this is where you can check the makeup of your  party in great detail, being able to examine any party member wether or  not they are in the camp at the time. (Will use the gearset of the  character when they registered to the Duty Finder) As well as allow  players to view any other information they may want to share (other  players memoir pages bassically togleable of course for privacy and  elitist jerk reasons)
Shared Inventory
Often  I have found myself in a Duty finder where the mage is running  dangerously low on MP in certain situations and as a career Alchemist I  often carry the solution to their woes on my person! Unfortunatly for us  when in a instance we are unable to trade items. So I can not give a  potion to the mortally wounded palladin, nor can I spare a strip of  steak to the Dragoon. With this system there would be a single bad that  all players could dip into during the instance allowing us to share our  combined characters wealth of provisions.
Limit Break Selection
Now I know this one will probably get me in hot water with some people but whatever!
As  it stands limit breaks are predictable and boring. I suggest that based  on the party makeup allow different limit breaks to be available, make  each job have it's on special limit break and give the party the 3 basic  slot types (Tank, Healer, DPS) and allow us to choose what limit break  we want giving some more variaty and strategy to the choices we make and  the party makeups we take into battle.
I'll leave balancing these limit breaks to SE!
Lore/Beastiary
How  often have you wanted to read more about a dungeon than the small spat  the NPC at the door gives? How often do you wonder what the history of  the named monsters in the dungeon are or basic information on the beast  that lay within the cavern you are about to descend into.
The camp system would give a perfect place to put textbooks worth of beefy information for the lore nut in all of us.
Memoirs
Basic  records on your time in this particular dungeon, wins/losses/loot  aquire whatever. give people an option to rewatch CS's from this  particular dungeon if they want another thing to kill the time.
Feast
One  of those things I noticed about cullinarians and Alchemists is the  lament of having much of any real impact on how they contribute to the  endgame scene. Allow Cullinarians and Alchemists to cook/concoct rare  and powerfull party buffs that last through the entire instance and is  not lost upon death. As this system is focused on endgame dungeons it  would give us a real reason to have 1-2 star recipes that DON'T DROP  FROM CHESTS IN DUNGEONS!
Before  we all jump to conclusions let me preface with this. This system is  entirely my idea and something I decided to write as a excercise with  the forum populace I in no way expect Square Enix to entertain my ideas  but I do think the logic behind the idea has some great potential.
If anything this was a fun topic to write about, let me know what you guys think.