I used 'Yourthaiguide' and I had a great experience. I requested a male guide who was well versed on Buddhism and could explain the political and religious symbolisms of the temples. I got an amazing guide who went to university in the US, spoke English very well, and had actually gone to high school at one of the temples. It was actually a very personal experience of him sharing his religious customs and symbols. I customized the tour to go to only the specific places I wanted to go. I had a great experience and I felt that the price was very reasonable. I chose to not have a car. We took cabs, riverboats, and walked some. It was amazing. I tipped 500Baht. I also bought his lunch. We had a great conversation at lunch. Total cost for the 7 hours was about $80. $40 in advance through PayPal and $40 (in Baht) upon completion of the day.