Wendii in her "Big Orange Ball" missive shares questions to spur creativity and requests we post in the forums open ended questions *we* use to foster creative (option-expanding) conversations.
I like "If every other area of our current operation remained at its current level of performance, what is the one area where change would have the greatest impact?" I added the question to a list of questions from the Jumpstarting Internal Relationships cast: https://www.manager-tools.com/2006/11/jump-starting-internal-customer-relationships
The question is from a book...I just cannot remember which. Anyone?

The 4 Disciplines of Execution: Achieving Your Wildly Important
The 4 Disciplines of Execution: Achieving Your Wildly Important Goals by McChesney, Covey, and Huling.
Page 32 in my version.
http://www.amazon.com/Disciplines-Execution-Achieving-Wildly-Important/…
In reply to The 4 Disciplines of Execution: Achieving Your Wildly Important by William Elledge
Dude...thank you!
I best get around to re-reading that tome!
You can find a lot of these ideas in retrospectives
Agile retrospectives are all about this kind of thinking.
Here are some examples.