The Night Country is listed as one of ten best Halloween books, via ScreenRant and Reddit. In fine company with the likes of Stephen King, Ray Bradbury, and Bram Stoker!
Ghosts and Halloween are a winning combination, and Stewart O’Nan’s The Night Country found a clever new way to blend the two together. Reddit user bittybro gave a great rundown of their favorite Halloween book when writing, “The Night Country by Stuart O’Nan. Ghost story that takes place on Halloween. Told from the POV of the ghosts.”
https://screenrant.com/best-spooky-halloween-books-reddit/

And from The Week, the novelist Elizabeth McCracken lists A Prayer for the Dying as one of her “favorite novels of the past 25 years”:

A Prayer for the Dying by Stewart O’Nan (1999)
This is one of my favorite novels of the past 25 years — about a small Wisconsin town hemmed in by a diphtheria epidemic on one side and wildfire on the other. When I have students who want to write a book in the second person, this is where I steer them: the finest example I know, a tour de force.
https://theweek.com/book-list/1017117/elizabeth-mccracken-6-favorite-books-that-tackle-tough-topics