I have the following in my .emacs
;;; This setting gives me a size 12 on a 1600x1200 display.
(set-default-font "-*-Courier New-normal-r-*-*-16-97-*-*-c-*-*-iso8859-1")
;;; This gives me full height of the screen
(defun resize-frame ()
"Resize current frame to 81 52"
(interactive)
(set-frame-size (selected-frame) 81 52))
(resize-frame)
;;; to recover size after readjusting it manually I use
(global-set-key [C-f11] 'resize-frame)
;;; On 1024x768 I use
(defun resize-frame ()
"Resize current frame to 81 41"
(interactive)
(set-frame-size (selected-frame) 81 41))