D1021 about sums it up pretty well. Either of the central atrium/food court areas on concourses A and B will do just fine. Even if you're plane isn't on A or B (which, if you're flying DL
it most likely will be), you can just hop on the people mover.
A secondary suggestion is to go to the end of any of the concourses to get a view of either the parallel north (8LR/26LR) or parallel south runways (9LR/27LR).
"The most terrifying words in the Engligh language are, 'I'm from the government and I'm here to help.'"-Ronald Reagan