See here for methodology, though now I am restricting the table to books actually set in Thailand. Also I should probably have posted this earlier, since some current estimates give Thailand a higher population than France of Germany.
| Title | Author | Goodreads raters | LibraryThing owners |
| The Windup Girl | Paolo Bacigalupi | 75,784 | 6,325 |
| The Beach | Alex Garland | 89,724 | 5,048 |
| Cockroaches | Jo Nesbø | 59,872 | 2,342 |
| Bangkok 8 | John Burdett | 10,751 | 1,876 |
| The Bridge Over the River Kwai | Pierre Boulle | 9,928 | 1,484 |
| Bangkok Tattoo | John Burdett | 5,429 | 1,021 |
| Mrs. Pollifax and the Golden Triangle | Dorothy Gilman | 5,181 | 852 |
| Fieldwork | Mischa Berlinski | 4,421 | 763 |
An unusually close race at the top, with The Beach only 6% behind The Windup Girl in aggregate rating. John Burdett’s series of thrillers set in Bangkok sound interesting.
A very white and mostly male take on Thailand here, as rated by Goodreads and LibraryThing users. The top book by an Asian writer is Hush! A Thai Lullaby by Minfong Ho, who is Chinese but was brought up in Thailand. The top book by a writer of Thai origin is A Wish in the Dark by Christina Soontornvat, who however was born in the USA and has lived there most of her life. Rattawut Lapcharoensap, author of the short story collection Sightseeing, was born in the USA to a Thai family and brought up in Bangkok.
I disqualified five other books which had been frequently tagged as set in Thailand by LibraryThing and Goodreads users. They were This Is How It Always Is, by Laurie Frankel (seems to be mostly set in Seattle); The Narrow Road to the Deep North, by Richard Flanagan (seems to be less than 50% in Thailand, with significant chunks in Australia and also Japan); The Geography of Bliss, by Eric Weiner (set in many countries, including Thailand); Platform, by Michel Houellebecq (mostly set in France); and The Orchid House aka Hothouse Flower, by Lucinda Riley (mostly set in England).
Next up is the United Kingdom.