I contacted this company when I arrived in Bangkok at about 2:30 a.m. By 7:00 a.m., I received an email that they could accommodate my request for a 2 day personal guide. I paid by PayPal, and Jean had the hotel call my room when he arrived.
Jean arrived promptly, and spoke English well. He was very open with his country, and was able to answer my 1,000 questions. He was kind, willing to do everything I wanted, and he looked out for my safety, as well.
The first day, we discussed all the options, and we visited all the major sites in Bangkok. The second day, we visited Ayutthaya, Thailand for the whole day. We took a cab (as it was cheaper than the private car that was offered by the company), and per my request, stopped at numerous ancient temples. We also walked over to where a movie was being filmed, and we fed baby elephants. Jean accompanied me into the bat caves in tiny temples, and gave me honest feedback about his country and all the sites that we visited.
Jean was also very knowledgeable about history, both of his country and of neighboring regions. He was also very tall, so I never lost him in a crowd. He was able to give me important information such as some Thai words, Thai cooking, Thai culture, and even more.
Apart from this company, if you have specific questions on itinerary, please feel free to PM me through TripAdvisor.
I would highly recommend Jean with Thai Guide.