Cambodia may well be the next Asian tiger with its combination of world heritage sites, tragic history, burgeoning business recovery (everything in dollars and riel), and hands on service industry. I recommend visiting the killing fields, not so much for the site itself (there are many all over Cambodia) but because the audio tour is well informed and one of the most humane. The narrator makes you aware of the past plus kindly asks you to contemplate humanity and how to be humane to it.
Then go to Angkor Wat and think about the wonders of what people can build in the jungle. The place is worth seeing at dawn or sunset. It will be hot at almost anytime you visit. It costs $20 to get in and that’s not bad for a world heritage site.
The town of Siem Reap (Siam Conquered) is very touristy but if that’s what you want, then go for it! There are still enjoyable things to be had. The dollar massages are still done well, the fruit with chili salt is still refreshing, noodles for a dollar (seems like it all costs a buck) are still greasy and yummy, the shopping still good (though not as cheap as to be dirt cheap). Surprisingly the prices are not as low as you might expect. A pair of “hammer pants” or ali baba pants cost $7! (I bargained down to $4). It is not expensive but not the prices expected. Everything is quoted in U.S. dollars but the locals can give you change in both dollars and riel, or a combination of both.
The Khmer people are graceful, sweet, and affectionate. Visit Cambodia for the people.