A couple of points here...
I don't have all of the information with me since I am travelling, but I would suggest that you look closely at spaces in ADT 2007. ADT 2007 actually has rules to automatically create BOMA standard spaces. It can also implement the DIN standard in Europe.
Second, dig deep into Revit 9.1 and you'll find an option panel to control how rooms are defined: face to face versus centerline, etc.
Finally, if you have polylines already for FacilityCenter, don't touch them. You can use them again in FMD. Use the Facility Link application with your AutoCAD. You can pretty darn quickly load those polylines straight into FMDesktop. If you decide to switch to ADT spaces or build a new building with Revit, just do that for the new construction. FMDesktop doesn't care what mix of various CAD or models you use. Mix ACAD, ADT and Revit all.
Watch soon for a couple of whitepapers on the FMDesktop web sites. One describes the various tools you can use to define the spaces. A new one will talk about how to implement BOMA standards.
Mark Evans
Mark Evans
Senior Product Manager
AEC Division, Simulation Product Line
Autodesk, Inc.