Hi Big Daddy,
Please check this list. I’m not sure it’s the best list but I think these places so attractive.
1. Sunrise at Angkor Wat, Siem Reap Cambodia; Everyone does it; you’d be amazed by how many tourists show up at 5:30am. You just have to know how to beat the crowds and where to sit for optimal unobstructed viewing.
2.  Angkor Thom, Siem Reap, Cambodia. Locals pronounce this temple “Uncle Tom,” and though it hasn’t been restored to the degree of Angkor Wat, it does have several interesting elements.
4. Artisans Angkor, Siem Reap, Cambodia; watch artisans at work in this trade school for disadvantaged Cambodians, then shop in the colorful store where authentic goods fly off the shelves. 
5. Take a Tuk-Tuk to Downtown Siem Reap; This nimble mode of transportation – essentially a 4 person carriage pulled by motorcycle – congests every alley, lane and road in Siem Reap. It takes just a few minutes (and about $2) to get to….
6. Pub Street and Siem Reap Night Market, an area with the vibe of New Orleans at Mardi Gras. There are plenty of restaurants and “spas”.
7. Tonle Sap Lake; Take A Boat to the Floating Villages; This is an eye-opening look at the abject poverty and subsistence living in the primitive fishing villages of Cambodia.
8. S-21 aka The Tuol Sleng Genocide Museum, Phnom Penh; Pol Pot, the Hitler of Cambodia, and his minions, the Khomer Rouge were responsible for the deaths of nearly three million Cambodians between 1975 and 1979. 
9. Phnom Penh
Cambodia’s capital teems with tuk-tuk drivers and street food vendors. Weave through the city, spotting roadside pagodas nestled amongst grand French colonial houses.
10. Sihanoukville
Fondly referred to as ‘Snooky’, the main reason to stop here is the beaches, beautifully sandy and not as crowded as Thailand’s. With six sandy spots to chill out in, you’ll be spoilt for choice. Less popular than Victory or Serendipity Beach, Otres Beach is usually quieter and a good spot to try your hand at windsurfing or kayaking.