Just an unscientific poll because I don't get to talk to too many other people building larger enterprise applications with WinForms.
How are you structuring your WinForms application? Passive View MVP? Supervising Controller MVP? Atomic Object's Presenter First MVP? Presentation Model (Model-View-ViewModel)? Using the CAB? Lumping everything into the Form's because you don't see the need for MV*? Something else?
What are your challenges? Automating tests against the UI? Cross screen communication? Cross screen state? Dynamic Menus? Division of responsibilities between the MVP triad pieces? Validation?
I'll gather up the results later. At a minimum I'm writing up some stuff on testing through the UI itself.