Chicago has the advantage of being dirt-cheap to run. No set, smallish orchestra, simple costumes. It also benefitted from being revived at a time where the show's cynicism and black heart matched the national mood to an even greater degree than the even more cynical 1975 original production.
Pajama Game IS (or was) a smash, and it's a revival I like(d) very much. But I think its hit status has been due solely to the presence of Harry Connick Jr., and the strong foundation of having had the thousands upon thousands of Roundabout subscribers to make it a tough ticket. If it returns in the fall without Connick, I'd worry about it.
Sweeney Todd had a couple of strong months, but has been living on discounting since then. No shame in that. It's never been a show that has lived long on either side of the Atlantic, so I give the producers credit for turning a profit on it and running it in the black. But I'm not certain it is a genuine box office "smash," in the way that Pajama Game was, or the Chicago and Cabaret revivals were when they opened.
Begin at the beginning and go on till you come to the end: then stop.