A Google search finds thousands of websites related to travel in Cambodia. Each website does list sites that tell the history of the Khmer Rouge era.
The Killing Fields
Tuol Sleng Genocide Museum (S-21)
The Documentation Center of Cambodia
Pol Pot's Home

http://www.tourismcambodia.com

If someone wants to discuss the Era with a local it might be best to start with one of the employees at these sights .

A look a Cambodia travel discussion boards will tell you that Americans and tourists from any other country are visiting Cambodia each year. Also a good place to read personal experiences from travellers.
http://www.lonelyplanet.com/thorntree/forum.jspa?forumID=24

http://boards.bootsnall.com/asia-travel-f17.html

You may also want to perform a Google search with the terms <Cambodia Travel and blog> to find personal accounts of travel to the country usually with pictures and personal commentary

If it is any indication The ATM's deliver American dollars and plenty of airlines fly there . According to
http://wikitravel.org/en/Cambodia#Talk
" increasing numbers of visitors are rediscovering Cambodia's temples and beaches. Siem Reap, the gateway to Angkor, now sports luxury hotels, chic nightspots, ATMs, and an airport fielding flights from all over the region, while Sihanoukville is getting good press as an up-and-coming beach destination. "

More sources about Americans and Cambodian Travel and relations
http://travel.state.gov/travel/cis_pa_tw/cis/cis_1080.html
http://asia.travel-mantra.com/asia-travel/foreign-relations-of-cambodia-216.html
http://www.loc.gov/rr/international/asian/cambodia/resources/cambodia-recreation.html
http://www.mfaic.gov.kh/