Brother,
Just some thoughts..
In your list of purge reports you could add R9312 to purge the F9312 security history file. It can get pretty big if you have security logging on..but retention period would depend on your policies
In a FAT client environment you could check for pending package deployment records. Sometimes a user logs in to say the PY enviornment after a long time and finds 5 mandatory packages pending deployment...
Monitor Update center for important fixes and updates
Review User profiles, and delete all temp id's that are no longer needed.
Review debug log settings. Ensure that no debugs have been accidentaly left on, on servers and pkg build workstations
You dont mention much about Server disk spce usage etc and also on DB side such as re-indexing etc. Did you want to keep this strictly to E1 and not cross over into Server & DB maintainance..?