In the spring of  2009 Sun Microsystems went live with their implementation of OBIEE and presented at the North California Oracle Applications User Group.  The original document is found here,

http://www.norcaloaug.com/seminar_archive/2009_05/Sun_Microsystem_OBIEE_Implementation.pdf

but I have also mirrored the file here,

http://www.artofbi.com/docs/Sun_Microsystem_OBIEE_Implementation.pdf

The document highlights some of the benefits of  bringing OBIEE into the organization along with pros and cons and usage of the BI Meta Data Repository.  At a minimum there are some great bullet-points here that could be leveraged for your next OBIEE presentation.