Thematically, Cannery Row is comparable to most of Steinbeck's other works: it is a novel that identifies with "smaller" people in the world, giving them a voice and value that other authors may have eschewed. Unlike many of his other works, however, Cannery Row is decidedly lighter in tone and content, and intentionally so. Steinbeck wrote the novel to help a World War II soldier forget the horrors he saw. As such, it is unsurprising that two parties serve as the novel's narrative focal points.
Compare to Carson McCullers' The Heart is a Lonely Hunter, which is structurally similar, contemporaneous, and provides an interesting contrast by focusing on what divides a small community...