Nice topic, however, i have just back from a 1 month trip to Vietnam, Laos and Cambodia, i took a private tour in Angkor and nearby in 3 days through a company (www.vietnameseprivatetours.com )
we visited Angkor wat and Kbal Spean and Bantey Srei, just dont miss out the Apsara dancing show, it is very authentic.

Cheers