I flew round trip ORD-JFK on Delta's 727-200 earlier this summer. Yes, while it looked very old and used from outside, inside of it I've got impression I was in well maintained aircraft.
Actually, after seeing it from the outside, I was pleasently surprised on board. I did like their brown interior.
In a way it reminded me of the classic looking train coaches in Europe; like the Orient Express enterior, you could see in episodeds with inspector Poaro
Needles to say, flight in 727-200 is one of the most enjoyable experiances. Aproaching JFK in that bird -- from the east, flying over the airport to the sea, and then making 180 degree turn -- is one of the most beautiful experiences in flying.
Going westbound (return trip to ORD), turns above Michigan city were as well mesmorising.
Give me choice of flying on Delta's 727s or some other aircraft, I'd have to think carefully to make a choice...