Having finished running through my 4E conversion of Chris Perkins' adventure Lich-Queen's Beloved, I've learned a few lessons about dungeons and adventure design. One of these is the importance of the architectural environment and the very elements of the dungeon itself. In Lich Queen's Beloved, the environment of the dungeon takes on an interesting role and challenge in and of itself in the adventure, namely in the types of doors that are encountered. Doors, I feel, are an oft overlooked source of hazards, terrain effects, challenges, and provocative dungeon dressing. At the end of this post, I also briefly touch upon a way in which we can all design dungeons with better (ie. more fun) secret doors.
What I'm trying to say is that we simply need more doors.