Reddit reviews The Poetics of Space

Umberto Eco's Six Walks in the Fictional Woods is a very accessible introduction to thinking about literature in a way that blends narratology and semiotics. It generally sticks pretty closely to talking about the stories he has in mind, so I wished while reading it that I'd had a copy of Gérard de Nerval's Sylvie on hand, among others.

David Lodge's The Art of Fiction used to be popular as a supplementary textbook in creative writing classes because it just uses nice examples to provide a basic language for talking about literature.

John Sutherland has a number of books intended for a general audience that either introduce basic concepts of literary criticism or that just make careful reading fun, e.g. How Literature Works, A Little History of Literature, and The Literary Detective: 100 Puzzles in Classic Fiction (an omnibus edition of the books he's probably most well known for).

Gaston Bachelard comes to mind as someone who, like Gass, is just a delight to read: The Poetics of Space, Air and Dreams, etc. I'd put some other writers writing about their personal relationships to reading in a similar category: Nicholson Baker, U and I; Virginia Woolf, A Writer's Diary; and even Alison Bechdel, Fun Home.