I'm not even talking about El Clásico. We have no margin for error in La Liga. As I said in the last comment, if we lose at San Siro we're still advancing in the CL comfortably. If we drop points against Getafe, the league will get really, really difficult. If we're being practical, the Getafe game is much more important.
And do you really think we need a morale boost? We haven't lost a game since April, surely that must make the squad very confident.
We have yet to beat a top opposition this season (apart from the copa), and I believe having one under our belts ahead of the Classico will do us a world of good
As far as the Getafe game I don't see the issue if we play a full strength side against Milan.
If we go with this vs Milan:
------VV------------
Mach--Pique---Abidal
-------Busi---------
---Xavi----Thiago---
------Iniesta-------
Pedro---Messi--Villa-
We could easily field this vs Getafe:
---------------------------------VV------------------------------------------
Alves(won't play vs Milan)--Pique--Puyol (rested vs Milan)-Abidal(rested today)
----------------------Busi (rested today)---------------------------------------
-------------------Xavi----Thiago(rested today)-------------------------------
----------------------Cesc(rested vs Milan)-----------------------------------
-------Sanchez(rested vs Milan)/Villa (rested today)-Messi--------------------
In that second line-up only
3 players + VV would have played 3 games during the week. Isn't that line-up just as good as the Milan line-up, if not even better?
That's the luxury of having a deep squad, you can play a seemingly full strength side against one team, make several changes and still field another full strength side 3 days later.