In all A8 models, the front seats are ample and supportive, combining cushiony softness at first with an underlying firmness that should make them all-day comfortable. They have great mid-back support, combined with headrests that are supportive without forcing your neck forward. In back, while the standard backseat setup has long cushions good for lankier passengers, there's simply not enough legroom back there in the normal-length A8; so do get the A8 L unless you're tight on parking space.
Plus, available on the A8L (and included in all W12 versions) are lavish individual seats in back that might just be cause to get someone else to do the driving. Four-zone climate control keeps everyone comfortable, the rear seats are power-adjustable, and the right-side one includes a footrest while the left-side seat includes massage and recline functions. Also on offer in either model is a two-panel panoramic sunroof that makes the interior considerably brighter without interfering with headroom. In either case, the A8 has plenty of trunk space, and the rather long trunklid allows a wide opening.
The A8's cabin is a very quiet, refined place, and while you won't hear much wind or road noise, you will hear the engine somewhat during acceleration. The air suspension system also recalibrates itself to Comfort, Dynamic or Auto modes, though it rides reasonably well in all three with not a lot of discernible difference on most roads (though we did notice a slight bit more road noise in Dynamic than the others on one particularly coarse Interstate stretch).