In Doun Praev there is a strong cottage industry of silk weaving where in fact most of Cambodia's silk product is produced. Here you are really out in the middle of rice paddies, hot and sticky, and you'd probably just as soon be getting on to Krong Kaeb or maybe Vietnam, but there are two sites worth seeing. In that context, don't necessarily go to Doun Praev, because it's not on the way to either of these. It's just used to categorize these sites since that's the district in which they fall (see directions below instead).
Probably most conveniently, just drive or arrange transport down Hwy 2 from Phnom Penh. It's a straight shot. There may be a ferry service of sorts between Doun Kaev and destinations along the Mekong River, but that is likely to be a bit time-consuming and involved logistically-speaking.
Most definitely you are going to need motorized transport to see the sites listed below, or a bike at least, if you're really intrepid, since they are out in the country.
- 1 Phnom Chisor (take NR2 about 43km south of downtown Phnom Penh, then turn L onto access road to temple.). 7:30AM-5PM. In the 11th Century, Khmer Empire king Suryavarman I built this temple to the Hindu deities Shiva and Vishnu. Known originally as The Mountain of Surya[varman] (The mountain of the Sun), it is perched atop a hill, and you can see a unique symmetric pattern of landscaping if you look below from up top (see image).
- 2 Phnom Da (Wat Asram Moha Russei) (from Phnom Chisor, take 203 east to roundabout then go south on unknown road), ☏ . This is also a Hindu temple created in the 11th Century, but it has UNESCO World Heritage Site status and also has written relics from the 4th Century. Unfortunately, it's at the end of a long road, so it involves quite a bit of travel.
Little eateries along the way
Probably you're going to want to just make this a day outing, but there is a pretty nice casino resort in Chrey Thum close to Phnom Da on the Vietnam border, which will soon be accompanied by another casino resort called Yong Yuan once it is completed.