My mother, sister and I went on this trip with Sammy as the guide - we highly recommend him! He spoke great English and was extremely communicative. We absolutely loved the summer palace which was a great retreat after the hectic and noisy Bangkok experience. The Ayutthaya ruins were great too though at noon, quite tiring for us. This was no problem to Sammy, who adjusted to our pace and wishes.
Apart from learning a lot about the sights we've seen, Sammy was very good in explaining all questions we had about Thai history, culture and society. He also gave us good tips about places to go and see in Bangkok, Chiang Mail and Phuket which we were to visit afterwards.
We found that this private tour gave us the opportunity to explore all the places for exactly as long or short in case of the more sun flooded temples as we wanted to, and that when we spoke to Sammy about our night market experience he even added a little stop along the way on an Ayutthaya market and gave us tips on what sweets and dishes to try. Also, when we decided that we wanted to have some fruit instead of the scheduled lunch, Sammy arranged the trip accordingly to our wishes.
Overall, a great experience and good value for money!