I was lucky enough to see him twice. In 2016 he did a walk-on duet of New York State of Mind with Billy Joel at Madison Square Garden during one of Billy's monthly concerts there (then Billy had the entire audience sing Happy Birthday to Tony, who was turning 90 the following week).
But the legendary performance was at the Houston Rodeo in 2000 in the Astrodome with 40,000+ in attendance. He still made it feel like an intimate supper club, even from a revolving stage in the middle of the arena 50 yards from the nearest fan.
The most surreal scene, though, was watching them set up. If you've ever been to the Houston Rodeo, you know that after the rodeo part it takes several minutes to haul the stage out and set it up, so they would fill the time with the chuck wagon races. Tony's band was on stage while they were setting it up. Through binoculars I watched these suave New York musicians in their $2000 Italian suits stare incredulously as the horse-drawn wagons went thundering around them like a cross between the Sooner Schooner and the chariot race in Ben-Hur. Nein's GF's uncle may have been one of them.