A while ago, i read a post in the wow-europe hunter forums (or in the american equivalent, can't really remember) where people discussed, which adventures had been their best in the game - and almost every hunter, who stated they had played since vanilla WoW, had the Hunter Epic quest chain in their Top 3.

For those that don't know, it was a questchain you made in order to get a bow and staff, with a "side" quest to get a quiver. The chain involved getting some items from raidinstances (MC and Onyxia, and Azuregos for the side quest) and then doing some challenging outdoor bosses on your own, which you had to defeat using special hunter abilities on each boss.

There was a similar quest for priests in order to get Benediction/Anathema. And Druid’s had to use their class-specific forms in order to get the Epic flight form. Paladin’s and Warlock’s got their riding mounts through a questchain, but it didn’t utilize enough class-spells, in my opinion.

The quests were fun, since you had to use class-specific spells, and you weren't allowed to get help from others (or else the demon-bosses would despawn), which made the encounters challenging and fun. As a hunter, it was fun to kite the demon in Winterspring, or melee the demon in Ungo'ro, using Aspect of the Wild and Wing Clip. It just made the whole chain feel epic, and you felt as if you had achieved something after completing it.

Even though this is a multiplayer game, i would love to have a class-specific instance implemented for every class, even though it would be somewhat difficult making 10 different instances with around 3 bosses in each. But it could be a nice addition.

So how would it work?:
In order to make it fair to everyone, as soon as one would enter the instance, your gear would be removed and a fixed set of gear would be given to everyone, for every available spec.

I imagine that the spells and specs each class had to use could be something like (just suggestions):

Death Knight: First fight could have you use your pets/ghouls/army of the dead, second a control fight with interrupts, death grip and freezing people and the third could have you utilize some tanking cooldowns in order to survive.

Druid: One boss where you need you to use your feral abilities and forms, one for restoration and one for balance. A bit similar to epic flight quest, but it can of course be done in a completely different way.

Hunter: A boss where you need to micromanage your pet, one where kiting is relevant, and one utilizing traps, wing clip and deterrence. Maybe also some aspect-changing involved.

Mage: A fight involving aoe, a fight using escape abilities like invisibility and blink, and one where you have to set something on fire and freeze something else ^^

Paladin: First boss would need you to be all 3 specs in a 3 phase fight (respeccing for each phase), second boss would need you to cleanse some poor souls (remember the cleansing-bot-duty from MC? ) and the third would have you bubble+hs. Finally, that combination is usefull ^^

Priest: Shadowspec on one boss, and a disc/holy on another boss would be needed. Fear/silence/shield could also be used in some form.

Rogue: A fight utilizing the stun abilities, one where stealth and vanish is needed (maybe combined with lock-picking etc), and the last fight where you have to stab everything in the back.

Shaman: A fight for every spec, with some twist in them could be awesome. Maybe a boss only killable by totems, placed at the right place at the right time.

Warlock: A bit like hunter, with a pet-micro managing boss, a boss involving a lot of dotting, and the last boss has you using your demonform. Chainfearing could also be of use.

Warrior: Tank the first, kill the next while dualwielding awesome axes/sword/maces and interrupt the third.

As I said, this is just to give an idea of the abilities etc needed to kill the bosses. The instance would involve no trash, and would thus remind a bit of Trial of the Champion / Crusader.
Furthermore, I think it should be in an instance to remove the chance for others to team up and kill you while doing it (at least on a pvp server), but even more so, to keep people from the same faction from helping you.
I’d like to get some feedback on this from everyone, and I hope we can keep the flaming and the tl;dr away 8)