Alright. This question will also help us to plan out our overworld, as whatever theme this dungeon will have, it'll obviously tend to match up with the theme of the overworld that it's placed in. Thus, we need to decide what theme this first dungeon will be.
Anyone ever play Teilyr's CoD Demo, or Revenge 2? Hidden Duality? LinkTheMaster's Night Rod Demo? ... If you have, this dungeon will be very similar to those. It'll be a standard dungeon romp Dungeon, with the usual hunt for keys, the map, the compass, bombing walls, killing enemies to reveal secrets, solving puzzles, etc. The dungeon won't necessarily have a "Gimmick," such as raising or lowering water levels. It's supposed to be something attainable to the relatively new ZC user, while still teaching proper level design and puzzle schematics.
Thus: I ask you all, ... ... ... what's your favorite theme? Let's just get a big ball of opinions rolling, and we can sort them out when we begin to get a grasp of what people love to see. :)