Siem Reap

Taxi from the airport is $5 assuming you can get him to actually take you where you want to go. If you book a place in advance you can almost certainly get a lift from the airport and often it will be free.

they are trying to rip you off. show up and hire a tuk tuk. there's plenty.

One last question, I'm quite sure of it guys.

Everyone seems to be quoting prices in US$. Is that the currency used or do I change it to Cambodian currency while in Cambodia?

Most things are paid in dollar in major towns. You will need very little Cambodian currency whilst in Cambodia.

Even the ATMs dispense US dollars! You get small change in riels (25c = 1000 reils etc). A tuk-tuk from the airport is $3. I found that meeting a tuk-tuk driver on arrival was a good way to choose. I paid $10 for the short circuit and used my LP guidebook.

Sad, but true. The dollar is so much of a common use that when you buy something in dollars (and sometimes even in riels), you're often given the rest in dollars as well. I have never traveled to a country where I have been given the rest in dollars. And I am not talking about big purchases: I was given dollars back from local restaurants!