The Happy Isles of Oceania is also worth reading. He paddles around in a portable kayak, and sees the parts of the South Seas that most tourists would never see.
I haven't read his rail travel books, but The Happy Isles of Oceania is one of my favorite books, travel or otherwise. Fantastic account of his travels in the South Pacific.
I agree! Theroux and Naipaul have an undercurrent of nastiness in their writing. E.g. the # of times Theroux describes someone's shirt as dirty in The Happy Isles of Oceania. Doesn't he realize that the people he's talking about live in huts and don't have money? I like reading them both, but won't like to meet them while traveling. Seems like they would be judging me constantly.