A few ideas:
- Keep the descriptions of items to find vague but with the intention of having something specific captured, in this sense they would truly be "clues" (ie: we know what we want and the teams need to guess the "right answer". Example: "The Gastown steamer surrounded by tourists on the hour" might be the clue for the Gastown Steam Clock.
- Make the descriptions vague with the intension of letting the team interpret them artistically. These are more like "hints" or "guidance". Examples might include "fill in your own ending" types like this: "The biggest red round...", "The smallest living...", etc. Might be good to make the majority of this type.
- The opposite of those things they have in magazines: "photograph this wacky caption". Examples: "Nice XML you have there!", "Don't worry, XFY can fix that for you!", etc.
- Perhaps some more cross-wordy, or math, or "located on the map here", types of clues (when we want specific "answers").
- Do some of each type.
- Decide whether or not to tell the teams what each item is worth. If we keep this secret, but let them know that some are worth more than others that would make things interesting.