I used to fly JFK-LAX every few weeks or so and really came to like these planes for all the reasons mentioned – fast boarding, schedule frequency, good experience in all classes. While they're getting a bit tired they will be missed.
Incidentally, after putting my old flights into Flighty last year, I found that I'd already flown most (maybe 13 or so?) of the A321T frames. Since I was close I decided I ought to try to fly all of them. Picked up the last two on a RT a couple weeks ago, so I'm now 17 for 17.