I recommend this tour if you are really interested in the history and culture of Thailand. The guide was very knowledgeable about everything and told me so much about the country, in fact almost too much.
The first day felt a bit stressed with the summer palace and Ayutthaya, in fact we did not spend enough time in Ayutthaya and just saw a fraction of the ruins. The itinerary required us to explore the area in the middle of the day, so it was also just too hot and I think it should be planned differently. I loved the second day, though: The walk at Erawan National Park was fantastic and we also spend a lot of time at the memorial in Kanchanaburi and on the railway. The last day was bit too short, we left Kanchanaburi for Bangkok at around 11.30am and I think that is too early for an advertised three day tour. However, the hotel we stayed at was fantastic it was the Royal River Kwai Resort and altogether, I enjoyed the tour.