Have you read Jean Stafford's "A Boston Adventure," published in 1944? It's the story of a young woman who grows up on the South Shore, working in a tourist hotel, who is "adopted" by a Back Bay brahmin and observes pre-WWII Boston culture from the inside. Stafford was married to Robert Lowell and A.J. Liebling, and won a Pulitzer Prize, and I think she's still worth reading though almost no one I know has ever heard of her.
Also, Van Wyck Brooks wrote 5 books about the growth of American Literature, of which 2 - "The Flowering of New England" and "New England Indian Summer" - have quite a lot of coverage of the Boston Literati of early and late 19th Century. I haven't read these in years, but I remember them being enjoyable.