I hired a private tour guide in Bangkok. It was fantastic. My request was "I want a male guide who was well versed in Buddhist symbolisms and architecture to tour the temple complexes in Bangkok" I used a company called "Your Thai Guide". I was contacted and asked if I had specific temples in mind. I named 3. Obviously the big temples of Wat Arun and Wat Phra, but also a smaller temple nearby.
I remember sitting on the floor with him in the main Buddha in Wat Arun. He quietly explained everything that I was seeing from the significance of the statue and the features to the political reasons behind some of the architecture. The third temple happened to be where he went to High School. He was very excited to show me the grounds. The stupas were actually gothic 'to impress the French'. It was definitely the highlight of my trip to Bangkok and I was so happy I did it. He was a very interesting young man who went to college in the US, so his English was excellent. It was so worth it.
I hired a private guide at Chichen Itza once and it was the same thing. A degreed archeologist who was part of the private guide staff at the complex. He led us on a fascinating tour (we got there at 8 AM when it opened) and he kept it very interesting showing us the 'theatrics' of the architecture.
Private guides and small group tours are the way to go.