If’n I were in command of developers…
Oh, I’m going to keep this very, very narrow – and not really going to encourage a lot of whimsy, either.
I would have them build an instance. Just one. It would be a mandatory visit for every class doing an “I AM” quest chain. There would be, of course, some catches.
For one thing, it would be a 5 man raid. That is, it would take 5 keys (no more, no less) to ‘unlock’ the door. The place would be on a multi-day timer. It being only 5-man, substitutions would be… discouraged if not disallowed.
Certain areas would require special keys to enter. There’d be an area for each class. Each class’s basic entry key would be enough in some places – so if you’ve a priest, you get to enter the Temple. There’d also be items that led to quests to allow you to get your basic key modified – the mask that you take out that leads eventually to the stone you set in your key that allows the Rogue’s Lair to be opened for example. (Or in Blizzard Terminology and structure, you also get a Rogue’s Lair key on your keyring.)
And then there’s the hard part. For every major spec of every class, let there be an event that ONLY is available when they are present. It may be hard, it may be (relatively) easy, depending on the rest of the quest-chain. Regardless, potentially 27 separate events that occur ONLY when a ___spec ____class is in the party.
That’s the core. Oh, there could be plenty of other reasons for the entry – gear to gain, quests to complete. But “more people” is not always equivalent to “more difficult”. And having reasons to come back again and again does still encourage multiple players to make multiple visits.
Of course, a major reason Blizzard likes 10+ people raids is, well, it prevents some class breaking the instance – either because the class is essentially dead weight, or counterwise they’re the critical element that makes “hard”… not. Making a good, challenging 5-man is actually harder. My two cents – well, a lot more by this time – has already been mentioned. Make some part of it special for somebody.
For what it’s worth, some classes wouldn’t have a I AM quest here – merely because they’re already there. Druids with the Elite Flight quest come to mind. Which means this isn’t even necessary. The smooth way that was inserted — and it was smooth — makes it plain a whole new instance isn’t a requirement. And almost every class wants/needs a good I AM recognition task. Please, blizzard, please do that for the rest of us. But again, if I were able to influence the developers, it’s the instance I’d be requesting.
5-man raid, multi-day, no overlap entry, potentially different for every combination of party. And make a (or the) critical component of the I AM questchain.
If’n, of course, I could direct the developers for a while…