Siem Reap is probably the most visited region out of Cambodia because Angkor Archaeological Park sits a couple minutes north of the city. Even if you are “templed out” from neighboring countries you have visited, you must visit the historical temples in Siem Reap for they are grand beyond imagining. If you are visiting for a few days it is highly recommended to use a tuk-tuk driver or taxi to see as much of Angkor and the outlying temples as you can fit in. You also have the option of renting a bicycle if you prefer, but some of the distances under the warm sun in high season require a lot of stamina.
A popular place to visit for locals is Kulen Mountain, which is yet to be overwhelmed with tourists. Visitors can only go before noon (unless they are traveling by motorbike, which is not recommended because of the muddy and arduous roads), and can only leave after noon because of one-way, muddy road conditions.
Siem Reap tends to have surprising multicultural elements. You will probably be directed to The Alley and Pub Street for a bite where you can find a diverse array of foods from fine French cuisine, Vietnamese noodles, Thai restaurants, and Indian curry. It’s recommended to venture outside of Pub Street area and try the tasty local Khmer cuisine. International NGOs have long contributed volunteers and educators to improve Cambodia’s poverty. Local children will try to sell you postcards, hats, scarves and books by selling to diverse tourists in their motherland tongue. Many locals can speak more than a few introductory words in English, French, Chinese, Korean, Spanish and more. Do your research before donating money or volunteering to make sure that an organization holds a reliable reputation.