You're right that Jitney is probably the closest thing Wilson has written to what would be termed a "well-made" play, but what was most memorable about that New York production was that more than anything the play is a great vehicle for a gifted ensemble of actors (the cast received an Obie for best ensemble).
I don't recall much use of ragtime in this production of Gem, but nonetheless the show ably captures the "feel" of turn of the century America, much like the brilliant production of "Joe Turner's Come and Gone" (set in 1912 and IMO Wilson's greatest play) that played on Broadway more than a decade ago.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
[http://margochanning.broadwayworld.com/]
"The Devil Be Hittin' Me" -- Whitney