Right now I’m in Siem Reap, which is where you stay if you want to see the Angkor ruins, which most famously include Angkor Wat. I know I have at least one friend who will be coming this way soon, so I thought I’d type up some suggestions for people visiting here.
First: before you come to southeast Asia, stock up on batteries if you’re going to be needing them for your camera or whatever. The batteries they sell in convenience stores here suck and start giving me the “low battery” warning almost the minute I begin using them (I’ve found this to be true both in Cambodia and Thailand). It’s not too bad cost-wise, because they’re so cheap that having to change them a lot isn’t expensive, but it is annoying.
The hostel I’m staying at is Green Town Guesthouse. I highly recommend it. Quality of the room is far better than expected given that I’m paying $10/night, even has air conditioning which is not guaranteed in this part of the world. (Though after having spent a month in southeast Asia without AC, I’m pretty well acclimated and 70 degrees Fahrenheit actually feels cold.)
You can see Angkor Wat in a day, but you’ll need at least two days to get a half-decent taste of the other ruins in the area. A one-day pass covering all the sites in the area is $20, and a three-day pass is $40, so you may as well plan on doing the do the three-day (unless you want to get the week pass, for $60).
I recommend getting around on a rented bike. It only costs $1/day. You have to be a bit careful to get a decent quality one, though. Today, I started checking tire pressure on a bike, and the lady running the bike rental responded by saying, “oh, I’ll get you a good bike” and went around back to get one of the bikes that was apparently for the savvier customers. Still only cost $1.
Aside from Angkor Wat, I’d make your top priorities Angkor Thom and Ta Prohm. Angkor Thom is abandoned capitol city of the Khmer Empire, now mostly converted back into forest. To the point where the former city walls now have trees growing into them. Wandering around there is a lot of fun, you get to say, “oh, what’s that little thing poking out from behind the trees” and it turns out it’s a HUGE structure that was just mostly hidden by the trees.
Ta Prohm is a temple that similarly got retaken by the jungle… but whereas in Angkor Thom, the trees are just around the temples, in Ta Prohm they’re actually growing into the temple. It looks very cool–lots of the Angkor temples look like the image you probably have from movies of an ancient temple in the jungle (possible because you’ve actually seen them used as locations for movies), but Ta Prohm is the epitome of that.
Oh… and having been to the Cambodian capitol Phnom Penh, I have to be honest and say that there’s no particularly compelling reason to go there. The main tourist attractions are depressing historical sites having to do with the Khmer Rouge, and while I did feel obligated to go see them while I was there and you might want to do the same, I’m not going to tell anyone to make it a priority. By all means, fly in to Bangkok, hang out there for a few days, then take a bus to Siem Reap and don’t bother going anywhere else in Cambodia.
ETA: “By all means…” here should be read as “If it’s what you want to do, then go ahead and…” I’m not saying you absolutely shouldn’t go anywhere else in Cambodia as an absolute. Whether you should do that or not depends on a lot of things. This post was written with some friends who are likely to want to take relatively short trips in mind.