How much time do you have between flights? What kind of shape are you in (EricH isn't kidding at the amount of walking that would be required).
It depends on where your gates are ... if you come in at a very low D gate number, turning towards C isn't horrible but the walk from C down to the aerotrain on top of it, makes it a long stroll. Go in the other direction and its a fairly short walk to the people mover that will take you to the main terminal, and a so-so walk to the aerotrain station to go to the terminal for LH - short ride and you're dumped right at the LH lounge (if that matters) and near their gates.
Safe Travels!