As suggested, go to the Flagship Lounge on D30. Plenty of seating options, self-service food and drinks, working and resting areas, showers.
There's also an Admirals Club by D15, which has also been recently renovated, but it's smaller and doesn't have much to offer, just the basis.
And I haven't been to the Club at E, but sure not worth all the walking.
American Express has a Centurion Lounge by D12, which some like.
But in my experience AA's Flagship Lounge is the best option.