Originally Posted by JPDM

Do the Wall on your day of departure. You need a driver in any case and he can keep your luggage.
On your full day, try to start the day at the Temple of Heaven before going to the Forbidden city. If you have time, you can continue on to the Lama Temple and or the Drum Tower area and have dinner at the Dali Courtyard.
I am not a big fan of the Summer Palace, especially in winter and it is out of the way.