Question on classifying books

I finally got round to adding a section on my website for the books I own/have read and recommend, and I am tinkering with the structure of the database that holds the titles.

The "genre" field is the one I am having trouble with - a huge proportion of my books are fantasy and sci-fi (both classed as "fantasy" in a lot of US book stores for some reason), but the odd one doesn't fit.

I've settled with "Humour" for things like Douglas Adams, Robert Rankin and Terry Pratchett books, but what about titles like:
- The Fourth Protocol & The Jackal (Frederick Forsyth)
- The Cuckoo's Egg (Cliff Stoll)

Currently I have these as "Fiction" as I can only recall the main (fiction) areas in the Waterstones I used to frequent as:
- fiction
- crime
- horror
- fantasy
- science fiction

Somehow "thriller" doesn't sound quite right, and strictly speaking The Cuckoo's Egg isn't even fiction.

Grrr, I might just classify them as cooking, self-help and travel for a laugh...

Would have thought they were clasafied as Thrillers.