You might also want to try using windmove which lets you navigate to the window of your choice based on geometry. I have the following in my .emacs file to change windows using C-x arrow-key.
(global-set-key (kbd "C-x <up>") 'windmove-up)
(global-set-key (kbd "C-x <down>") 'windmove-down)
(global-set-key (kbd "C-x <right>") 'windmove-right)
(global-set-key (kbd "C-x <left>") 'windmove-left)