Budget (2014): If you stay in dormitory rooms and stick mostly to street food $15 per day is possible. You should be fine with $20. Angkor Wat admission is $20-60, depending on which pass you buy. If you don't go to Angkor Wat (but please, go to Angkor Wat) then your budget will be closer to $15 per day. If you do go, a $20 daily budget should be plenty.
A pretty standard, large city in Cambodia. The city itself is rather boring, but there are attractions nearby, including mountain temples, bat caves, and a bamboo train.
Sleepy little town, alongside the Mekong River. I really dig the relaxed vibe of the city. It's a great respite from the busy Phnom Penh, and there are dolphins nearby. It is also close to Laos, so a great place to stopover before catching a minivan/bus.
Largest city in Cambodia, also the capital. It's ok, I guess - not really a huge fan of the vibe. For a city so modern, I was surprised by the terrible sidewalk/road infrastructure. It's a pain to walk around, and is also slightly more expensive than other places I've been. There are nearby sites such as the killing fields (which I decided to skip).
Fantastic place, home to the Angkor Wat complex. It has become a tourist town, but retains a wonderful vibe. There is a large marketplace downtown, as well as the awesome Pub Street, where you can get 50 cent beers. There are also lots of cool museums to check out.