> With saving, I usually add a confirmation directly next to the save button, so the save button itself doesn't change state (people often like pressing save multiple times!).

There is no problem with the button changing states as long as it only happens after the current document state was successfully saved and becomes active again when you make changes to the document. That way the button doesn't represent the outcome of some action but the sate of the document - unsaved changes = button enabled, no unsaved changes = button disabled.