Steve Eichert shares a story that sounds familiar:

When she started her basement project she had no idea what she wanted.  She knew she wanted a finished basement but she didn't know any of the details.  When Sonny (the contractor) asked her to tell him what she wanted she didn't know what to say.  Rather then try and force my mom into a strict plan Sonny decided to start with the most important aspects of the basement, walls!  As he finished each stage, he would come back to my mom (and dad) and ask them what was next.  A couple of times Sonny would finish something, but would then tear it down and do it another way based on the feedback he received from my parents.  Had the project been done differently this would not have been possible.  The incremental construction allowed my Mom and Dad to take a step back if they didn't like something, and it also allowed them to put off some of the details they weren't ready to think about.  In the end they probably spent a little bit more money, but, they were a LOT more happy.

The reason this sounds so familiar is that this same thing happened to me and my wife. Granted I was the contractor and she was the customer, but the process was the same. At first she knew she wanted a bedroom in the basement. She didn't really know how she wanted the hall layed out, where she wanted the doors or closets, etc. So I drew some chaulk lines on the floor and got her to talk about how it felt. Then I framed in the walls. During the framing we realized that one of the doors wasn't in a very efficient place, so we moved it. After the framing was done and the drywall was about halfway up, we realized that we should put a coat closet in. So down came a small chunk of the framing, in went a new pocket door and a closet was added.

This kind of thing is the essence of agile project management.

BTW, I don't know if I already mentioned it here, but you should read Lean Development and the Predictability Paradox by Mary Poppendieck.