My airline flies 737-800 series aircraft and we have them configured to 175, and the cabin is really very spacious. We offer a greater pitch (distance between seats) than most other airlines do, along with full leather seating with fully articulate headrests, state-of-the-art digital entertainment systems, 2 huge galleys which offer hot meals, and lavatories with baby changing tables.
Our cockpits are also very advanced, with full automation of flight controls and flight management from take-off to wheels-down. Along with heads-up displays and cockpit security, we have what many other carriers only dream of. Can't be beat, believe me!!
We retired our fleet of 727s almost a year ago. DC-9s are still flying (AirTran, the former ValuJet flies them exclusively - they are almost 33 years old!).
L-1011s were a favorite ship of mine. Very smooth and quiet in the cabin, but high service demands and limited parts availability caused the retiring of most of these aircraft worldwide.
The next to go are the 747-200 series. Some companies still fly them, but alas, they are getting old and uneconomical. The Boeing 777s and 767s are replacing the 747s on long-haul routes internationally.
Airbus, of course, has its own market segment with considerable success, but the cockpit is designed with a different purpose. It isn't "pilot centered" as the Boeings are.
Nice thread!! I always enjoy talking about my first love, FLYING!!