After seeing " Jazz on a Summer’s Day " many times ( about the 1958 Newport Jazz Festival) I would have loved to have been there and to have seen it live.
Miles Davis and the “Birth of the Cool” band- Royal Roost, 1949
Any Jimmie Lunceford performance, just to see what the fuss was about.
One of Art Tatum’s “garden party” performances
Any of the early 1900’s performances, especially by someone who never recorded (Buddy Bolden) or whose recordings weren’t as good as they could be (Freddie Keppard).