Also: any of the historical fiction by C. S. Forester, Patrick O'Brian, Bernard Cornwell, or Kenneth Roberts.

I didn't add the first two because they are on the "Water, Water" list, but I'll look into the others.

You could go with with Emily of New Moon instead.
For Colonialism, The Siege of Krishnpur, JG Farrell, The Quiet American or The Heart of the Matter by Graham Greene, A Fine Balance by Rohinton Mistry. ETA: Sorry, I see you already have those Graham Greene books.

For California, you could include a lot of Didion novels, but I would pick Play it As it Lays. Also, I would include The Crying of Lot 49 by Pynchon, Day of the Locust, by Nathaniel West.

I find this harder to do with books than movies or music.

colonialism: Heat and Dust by Ruth Prawer Jhabvala.

Non-fiction book for religious figures and settings is The CHeese and the Worms by Carlo Ginzburg

OMG, Warner Herzog is turning that book into a film. I think that will break my brain.

For Books -- Booked to Die and The Bookman's Wake, by John Dunning

I'd put The Handmaid's Tale in Religious. Would John Wyndham's The Chrysalids fit?

Windfollower by Carole McDonnell would fit in either religious or colonialism.

Well, the "book" books are pretty centered on reading or writing.

Then Anne of Green Gables or Emily of New Moon would definitely fit. Emily would probably be better than Anne, actually.

In the war category, I'd add John Del Vecchio's The 13th Valley. Follows an infantry unit in the Vietnam War.

Never mind. Oooops.