I'm with you. Sebesky's arrangements make reasonably pleasant home listening once or twice, but I can't imagine paying money to listen to them played in concert. I agree with your comment further down about the Sondheim: A Musical Tribute overture, but in general the various symphonic suites I've heard from musicals are not pieces I'd want to hear in concert. There are a few exceptions, but honestly most of them are just not musical interesting enough. It's not necessarily the fault of the arrangers. I feel the same way about concert suites of music from operas.
On the other hand, I do sometimes wonder why some of the great Broadway overtures don't get taken up by symphony orchestras more often. I don't think I'd want a whole evening of them, but even that might work if the program was well-chosen and structured smartly. There are some really great ones. The three to six minutes they generally take are well sustained in the best of them, and they'd make nice filler pieces even surrounded by masterworks in symphony programs.
When Broadway composers write music that is meant to be purely instrumental, those pieces sometimes sustain themselves nicely. There was an orchestrated version of Sondheim's early Concertino for two pianos, and that might be worth playing in concert. I've only heard the original version for two pianos, but that is a good piece that holds interest through its 14 minutes.