My wife and I took a small group, dawn tour of Angkor Wat followed by Ta Phrom (westerners call this the Tomb Raider temple, to the dismay of the Cambodians) and Angkor Tom. Our guide, Phi, was very informative, helpful and knew all the great photo spots. (He even took some pretty inventive pano shots for us). Phi also had all of the history at his finger tips, and we felt we learned a lot, without feeling overwhelmed. (There's over a thousand years of history here!) Dawn is a good time to start, so you can beat the heat. Hotel pickup is just after 4 AM and you are driven to the ticket office to buy your ticket, before the tour commences. Due to drainage issues and drought at Angkor Wat, there is only one pool of water and the crowd got pretty raucus, as people jostled for their photo ops of the temple's reflection in the pre-dawn light. No fault of the tour guide there, who took great care of us. The temple complex is truly vast, mind blowing, beautiful and thought provoking. A day doesn't really cover it, but if you only have one day, I would highly recommend this tour company and this tour.