We visited Valley of the Temples in August 2012. We went in the early evening, as we heard the temperatures could be brutal in the heat of the day. I would actually recommend going at dusk. There were were less people, and the temples looked great against the sunset, as well as lit up once the sun went down! My one gripe is that there isn't that much signage telling you what you are looking at. We had hoped to take a tour with a guide we booked online, but he was a no-show. You may want to read up on the Temples beforehand, or bring your own guide.
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