I made 2 copies of the main settings file that is located at \WoWfolder\WTF\Config.wtf
This file holds all main settings like: default resolution, graphics quality, sound, etc.
One copy is named ConfigHR.wtf and holds my high resolution (and high quality) settings for WoW.
Another copy is named ConfigLR.wtf and holds my low resolution settings.
I have 2 batch files: 1 copies to ConfigHR.wtf to Config.wtf and it is called "Set highres.bat". The other does a similar thing for the other wtf file.

When I multibox, I start all clients from keyclone, which gets them automatically resized and in position.
When I play regularly, I start my 1 client manually with a shortcut through avoid the keyclone resize.

The batchfile just holds something like this:
Code:
@echo off
copy ConfigHR.wtf Config.wtf /Y