A config.sup is going to be specific to your organization and standards. Remember, whatever you put in here users will not be able to change. Don't lock down too much, or you'll have a revolt.
I focus on things that affect model or data quality, not preferences like datum display. Also keep in mind that options that can be used more than once like 'mapkey' or 'search_path' can't be put in there as it will only recognize the first instance.
Edited by: dgs