Cambodia is amazing was there earlier this year, what you want to know??
Cycle your way around the temples of Angkor if your going to siem reap so much better a than tuk tuk get a three day pass or more if you have the time see all the little temples on the way between the main ones, where its only you there. also plan your day to avoid the main tour groups, go at the times they aint in the main ones.
Also hit sihanoukville laid back beach bars BEER IS 50c ALLLLL DAY, good night life and just real good/chill.