It's about a 6 hour bus ride to Phnom Penh, but it went by fast. The seats were relatively comfy, and we were entertained by a muted Jackie Chan movie with Vietnamese subtitles.
Despite its reputation, I liked Phnom Penh. I could sense its undercurrent of socio-economic problems, but it wasn't Saigon! I was ultra-cautious when we got off the bus, but the tuk-tuk driver who'd been soliciting the spot between my unfocused eyes for 10 minutes was actually a really nice guy. We hired him for the whole day: to our hotel, from our hotel to the palace, from the palace to the russian market, then to the night market and back to our hotel for only slightly higher than the local price, $12 in total.
Or hotel was near an interesting park (actually a huge traffic circle) with elephant rides and troops of wild monkeys.
The palace was very nice. It's still the residence of the King, though now he's tucked away in a minor building. We skipped the Killing Fields for another lifetime.
Shopping in Cambodia is an ordeal for me, but a true feast for a haggle-monster like Jenny. I played the reluctant keeper of the purse while Jenny would slash prices to under 1/3 of the outrageous starting price. Very often I was racked with Jenny pulling on one arm and the shopkeeper pulling on my other arm.
We had dinner at a fairly expensive Western restaurant, but had a nice sample dish of Khmer desserts. They're pretty similar to Vietnamese rau cau (fermented jello from algae), sweet soup and bean cake.
The road from Phnom Penh to Seam Reap was over 5 hours but seemed much, much longer. The minivan was not nearly as comfortable as the bus, and our fat, drunk neighbor who was constantly laughing and snorting into his cellphone put us in something under "coach." Though I probably shouldn't complain, the local buses were crammed with tons of crap and about 20 passengers hanging on the outside as an afterthought. Many, many times I'd prepared for death as a bus came barreling down the wrong lane towards us, or vice-versa. Sometimes we had to stop for cows or, outside a pagoda, people collecting money while a very, very unfortunate guy in a huge costume dances in the hot sun. We were very smart to fly back to Saigon.