Add a new hack: Mark subtree DONE along with all subheadings
Bernt Hansen [[http://permalink.gmane.org/gmane.emacs.orgmode/44693][suggested]] this command:
#+begin_src emacs-lisp
(defun bh/mark-subtree-done ()
(interactive)
(org-mark-subtree)
(let ((limit (point)))
(save-excursion
(exchange-point-and-mark)
(while (> (point) limit)
(org-todo "DONE")
(outline-previous-visible-heading 1))
(org-todo "DONE"))))
#+end_src
Then M-x bh/mark-subtree-done.
See http://permalink.gmane.org/gmane.emacs.orgmode/44693 for a discussion
of this need.