Hiya JVP!

>Consider this...
>
>You are designing - or possibly re-designing an application. The primary user - interacts with the app for at least 5 hours a day. He/she has a routine - a workflow that works well. As the developer - you do not - nor will you work with the app for as long as that person. In addition, you will not work with the app in the same way. Often, developers place too much of thier own bias into a UI.
>

I think this points up to the completeness of your upfront analysis. Workflow analysis (maybe as an expansion of CRC cards) should point you in the right direction. Also, simple alpha-testing will also uncover UI flaws.