If I understand you question correctly (I'm used to Emacs, but not aquamacs), your "panes" are called "windows" in standard Emacs terminology.
With standard key bindings, you can use C-x o
(binded to other-window
) to switch between windows.
There are also plenty of extensions allowing to manage windows. One of them is windmove
, which allows switching between windows using S-<arrows>
key bindings.