The Bellport Gateway Playhouse, on the south shore of Western Suffolk, used to be the place to go for the best "near-Broadway experience." A comfortable, intimate little theater with live musicians and leads who belonged to Actor's Equity and had some good credits. I saw very good productions of South Pacific and Fiddler on the Roof there. Their shows were reviewed in Long Island newspapers and often in the Times.
I think that they may be past their prime now. The number of their seasonal shows dropped from six to five. They bought and renovated an old theater in nearby Patchogue, which is not so comfortable and intimate, and use if for many of the shows that figure to be the most popular. This year it was Billy Elliot. At they playhouse they presented Nice Work starring Sally Struthers (in the past they didn't fish for celebrities, giving talent first priority). I don't know what part Sally played since she is 68.
They are also always fighting with the residents of this very toney village over noise and traffic. Oddly, just a few miles north of the prestigious Bellport on the water is the most violent and gang-infested area on the Island.