I use a 4-4-2 diamond formation with Real Madrid.
I have to say that I am still experimencing with my formation so it isn't the final one:
-------------------Casillas--------------
---Diogo---Arbeloa---Woodgate---Carlos
-----------------Gravesen---------------
------Beckham-----------Zidane-------
-------------------Guti------------------
-------------Ronaldo--------------------
----------------------Raul---------------
When I substitue I rotate a bit with Raul, Ronaldo, Guti, Zidane, Robinho and Baptista.
I'm using arrows too, so when Diogo runs upward the field, Arbeloa goes to fill out the center midfield AND the Right Back. When R. Carlos runs up, Gravesen goes down to play a Left Back.
The next thing I have to look into is the Man Marking and who's going to start in or going to sit on the bench. I have to test all the new players like, Arbeloa, Diego Lopez, Javia Garcia and so on.
But my formation is still a work-in-progress.