Mike Mearls, old-school devotee and a lead designer at WotC for 4E, exhorts folks wanting to design great 4E adventures to "Build your adventures in OD&D":
"Compelling locations, mysteries, puzzles, weird phenomena, *stuff* that the PCs can poke, prod, and inspect. These are all the things that make D&D compelling. They show off the spontaneity, immersion, and creativity that arise in the exchange among players and DM.
In Search of the Unknown is a great example of this effect in action. The dungeon in that adventure is empty of monsters and treasure. The DM is supposed to add that stuff. Instead, it features an overgrown garden of massive mushrooms, a chamber of mysterious pools, hidden chambers, details and color that suggest the dungeon's history, and other elements that make it an interesting place to explore. Reading the adventure, even without monsters and treasures, is fun. You want to know what's in the next room."
More at the link.
Might I suggest WotC re-release some classic editions to help us with that? ;)