In order to prevent users from creating sub-sites I created a custom permission level that identical to Full Control but has "Create sub-sites" unchecked. Turns out, users can still give them self or others Full Control, which then allows them to create a site.
What changes can I make to my custom permission level that will allow site owners to do just about everything except create a new site (and grant elevated permissions)?
By the way, we do not have access to the farm or Central Administration.