To start things off, I say avoid remaking the first quest, and avoid making something like DemoQuest.
The problem I had with DemoQuest was that it wasn't accessible to everyone. I remember playing that thing a long time ago. It was extremely difficult, and things were well hidden. I never finished DemoQuest for those reasons.
I'd like to suggest something a little more simple. Make the quest be a procession of screens, one after another. Each screen should showcase a new feature, or a few new features if they are related. Avoid hiding parts of the demo. What you should have is a showcase. It shouldn't be challenging to see all the sights. The purpose is of course to show off new features.
I kind of draw these ideas from the recent Half-Life 2 Lost Coast display. It was a straightforward, very easy level, that was full of new features with commentary along the way. Can you possibly document each screen to tell about the features on that screen?
I personally am not yet accustomed to the new features, so I can't say much for the feasibility of my plan having been off the ZC scene for so long. However in any case, I think that the "spirit" of my suggestion will work well.
