Hi Steve ,
STEP files can be imported into a lot of programs these days.
It's probably worth doing some research with your customers and find out what format the majority would like to use with their software.
I was not familiar with the term BIM and checked out the wikipedia link. Pretty generic. Then looked up file imports into Revit:
Looks like STEP is not supported in Revit. But SAT is supported.
I will take Mike's suggestion though to try to find out what the customer's might want to see.