I have used SiamRoads quite a lot, and in particular Mac, in Bangkok. See other comments sbove. He is very good, knowledgeable about Thai history, and the gay scene. He occasionally has issues, ie disappears for a few days, but he is good. I usually pay him 4,000 for a day, which is over the odds, but never mind! I get him to come to the Meridien to have breakfast, and we go from there.