It has been my experience that current and backlist books from the major publishers have the same availability at Amazon and Sony -- also Fictionwise, BooksOnBoard, and the other online e-Book stores. Amazon has more of the self-published stuff because they actively recruited the authors to use their publishing software and interface.
I suspect that our library here at MobileRead contains many books that you would enjoy, particularly since you say that you enjoy "anything well-written". I took a quick look into the library looking for books set in Asia, but all that popped out at me were adventure books set in the South Seas.
Read the best books first, or you may not have a chance to read them at all.
-- Henry David Thoreau
Currently reading: Kiln People by David Brin (MM Paperback)
... A Play of Isaac by Margaret Frazer (Kindle)
... Birthright by Nora Roberts (Audio CD)
Books read in 2009: 117