The class combination doesn't really matter- I dual a hunter and a palladin.

The pally is set to follow my hunter (i have the pally wow window minimized as I don't need to use it) and all the needed buttons are macro'd on the numpad. Most of it is done through using target=focus, and I have one to set my hunter to focus (but can easily be changed if some one wants to borrow him ^^) - then it's just different buttons for healing the hunter, the pet, or himself. Different blessings, auras, 2 different mounts etc. Cake

The formation stuff I wouldn't have said you need for a 2man as the non-main char will just step in behind your own.

With regards to the 'lag' issue you mentioned earlier - there's 2 possible sources. First, and least likely is your latency - if you're net connection can't handle both, one tends to get priority and it would make sense that it's the window you currently have active. Second, and most likely (as it's the problem I have at the moment) - my cpu can barely keep both instances of wow running at full speed - the main window (my hunter) tends to stay full speed - but when things get busy (ie running into the middle of an AV zerg) theres a lot of work for the cpu - my pally tends to fall behind as windows essentially puts it on hold - stopping the movement commands being sent to the server. I'm often turning around to go collect him.

Possible solutions; use 2 seperate computers, or upgrade the one I have. Neither are an option at the moment so I just make do.