I'm planning my first trip to Cambodia in December. In fact, it's my first trip to Southeast Asia. I'll have about 12 to 14 days and could use some advice on developing an itinerary. Cambodia is the top of my list, but since this is my first trip to Southeast Asia, I'd like to see as much as possible. I'll be flying from the US and was thinking a couple of days in Thailand, then on to Siem Reap and Phnom Penh and then ending the trip on a secluded beach somewhere - not sure where ?? Any insight?