I generally find the dungeon experience to be linear and less than what they could be. Most dungeons follow a similar linear path, Trash-->miniboss-->trash--Boss, to completion. There is usually nothing to do except kill your way to the end. Most of the challenge is stacked into "boss mechanics" which results in "do this now" or die gameplay.
I would like to offer a better suggestion, what I call global mechanics and the radial dungeon. Rather than a linear path well instead provide a setting. The setting might have a number of smaller paths radiating out from it. Rather than going from A-->B it will have a different type of gameplay including the folllowing:
The defeat of the dungeon will not necessarily be a boss kill but the completion (or failure) of what i call global conditions. Global conditions are kinds of like smaller tasks players can complete while they participate in the dungeon. The more global conditions you can satisfy without failure the better reward you get.
so there will be a number of tasks to complete but most of them are optional. This allows us to dramatically improve both the difficulty and replability of dungeons.
I will explain by example.
You and your team has been charged with going to castle greyskull and investigating the undead attacks in the area. When you get there at dusk you see the courtyard is teeming with undead who break down the door as soon as you get there. Your first task is to get past these undead and repair the door.
Once repaired the undead will keep beating on the door the entire time. You need to keep it repaired and failing that keep them from overwhelming you. You have to survive until dawn. You can find supplies to keep the door repaired in the castle keep. While your holding down the door monsters will come up from the basement.
The second stage of this dungeon is to find all the survivors that are scattered throughout the castle.
The third stage is to find a sacred object hidden somewhere in the house.
The Fourth stage is to go into the basement and destroy the monster generator down there. In this case the monster generator is an optional miniboss.
Your reward is based on what you accomplish in the dungeon. The global conditions.
If you ( at least 1 player) survive until dawn you get the Wood chest
if you survive and additionally save at least 5 survivors or find the sacred object you get the copper chest
If you survive, save 5 survivors, and find the sacred object you get the silver chest
if you survive , save 5 survivors, find the object and complete the optional boss you get the gold chest
if you save ALL the survivors, find the object and complete the optional boss you get the platinum chest
so the only critical part of the dungeon is to survive but if your strong enough to complete the other objectives you get rewarded for doing so.
In order to complete these objectives your team might need to split up and use strategies other than kill your way to the end. The following mechanics will be at play.
Surviving until Dawn is the Critical mechanic to pass the dungeon.
The door is a maintenance mechanic. Someone will need to get the wood from elsewhere in the castle and keep the door repaired.
Saving the survivors is one of two active quests. The survivors are in random locations each time in the upstairs areas
Finding the sacred object is the other active quest The sacred object is in a random location each time in the basement areas
The boss is also optional.
In order to complete all these tasks before dawn you will likely need to split up your forces. If you want to complete all the tasks you will have to determine who will do what. Someone has to keep the door repaired. Others will need to save the survivors and find the find the object and then the optional boss needs to be faced. Some objectives may not require brute force. Stealth might be the better strategy. Not everything needs to be killed so some things might just be avoided too save time.
Its another way to look at dungeons and it melds perfectly with my role mitigation since roles can be more fluid with that method. Most of the action stems from a central location where players can strategize to complete the radial tasks. I want to give players time to talk to each other in dungeons. Additionally some players are better suited to some tasks than others so they could decide who should do what.
ill post a few more examples after. There are a number of ways to set it up.
.33 of a second to midnight