The upper deck
The 747-8 upper deck borrows cabin architecture from the 787.
The upper deck of the 747-8, showing the curved ceiling and indirect lighting taken from the 787.
The upper deck is effectively a separate cabin: its own galley, its own evacuation routes, and a floor area that cannot be extended. Airlines have generally used it as a premium cabin since the 747-300 stretched it — a long way from the lounges and piano bars of the first 747s.
The seating is typically 2-2 in first class and 3-3 in economy, against 3-4-3 downstairs, which is much of why passengers seek it out.

