Dear Esther,
So nice to see you in Vietnam! What are the chances we'd book the same hostel in Ho Chi Minh?! Anyway, below are my tips for Cambodia which I'm also putting on my blog, I've got some general stuff first and then what I did/enjoyed/despised listed by place.
Money
The main currency in Cambodia is the American dollar. They also use their own currency (the Riel) although mostly as change. 4000 riel is a dollar so if you want to pay for something that's $2.50 you could pay $2 and 2000 riel. It's surprisingly easy to pick up. ***WARNING*** There is a ridiculous system in Cambodia where shops won't accept old, damaged or torn notes. Check your money when it's handed to you. Also the ATMs give out $100 bills try and break these before going to the islands or anywhere rural.
Siem Reap
We stayed at Lub-d in Siem Reap in a ten bed female dorm. It had new a beautiful facilities, solid, comfy beds with stairs instead of ladders so being on the top bunk was fine. The dorm was silent at night, which was lovely. It has a pool and a nice bar. It did feel more like a hotel and it was perhaps the least social place we stayed although there are events and the staff are very friendly.
We chose the three day option for Angkor Wat and were really glad we did. It's $62 for the pass and we ended up spending another $90 for a tuk tuk for three days. We arranged this with one of Lub-d's drivers and could had probably got it cheaper if we'd asked elsewhere. He did have free water on board through which was very useful!
You'll have already read about the temples I'm sure so I shall limit myself to a couple of sentences here. On the first two days we started super early which worked as it gets really hot and/or rainy around midday. My favourite day was the river carvings at Kbal Spean and Banteay Srei, the gorgeous pink ladies temple, which are a drive out of Siem Reap.
I'd recommend getting lunch from a bakery before going to the temples as your driver will try and take you to the more expensive restaurants where they get free food. The Scandinavian Bakery is close to Lub-d, we got lunch there.
Siem Reap to Battambang
Lub-d booked us on the Mekong Express to Battambang which was one of the nicest buses I've been on. Really easy journey which only takes three hours. I didn't take the boat between Siem Reap and Battambang but I heard that it is horrible.
Battambang
We stayed at Pomme hostel in Battambang and loved it. It has little cubicle style single rooms, a funky bar that attracts locals and expats and very friendly staff. We did the hostel run afternoon tour to the (original) Bamboo train and bat caves which was very enjoyable. It cost $8 for the tour and $5 for the train.
We also kayaked down the river in Battambang booked through Green Orange Kayaks which was very exciting. Although, due to some slightly dodgy directions, we left the boat in the wrong place and they thought we'd drowned... Using MapsMe and a waterproof phone cover and getting our hostel to ring them when we got back would have prevented this...
My other top tip for Battambang is the Phare Ponleu Selpak Circus. My circus loving friend Kirsty was desperate to go and she was not disappointed. It was excellent and imaginative. TBH I don't really like circus that much and I loved it.
Battambang to Kampot
***WARNING*** We got the Rith Mony night bus (booked by the hostel) and it was a nightmare. There were cockroaches and other bugs everywhere. The second leg was in a minibus which the driver had jammed full of stuff he was delivering so there was no leg room. Don't let anyone book you on this company. Worst. Journey. Ever.
Kampot
Despite my distrust of this infamous chain of party hostels we stayed at the Mad Monkeys in Kampot. It turned out to be very fun, although we went for a private room rather than risking the dorms. Also our first private room stank of paint and didn't have a door handle so we got a free upgrade.
On our first night there we did Captain Chim's sunset tour. It was $5 with one free beer which is not the best deal you'll see on the promenade. It also had no toilet or bar. But, we had it to ourselves and it took us much further up the river than the pub boats and we actually saw a fire fly! Just the one though. Captain Chim's rickety old boat is great, maybe take a couple of extra beers and a she-we.
We did the hostel run jungle trek which was $8, quite muddy, but enjoyable. I did fall in a river and almost get washed away... will tell you about it over a beer.
Our big activity there was Climbodia which was EPIC! It's a bit pricey at $40 for half a day but well worth it, it's been described by several friends as the best thing they did in Asia. You do climbing, ab- sailing and traversing and then a climbing session in the caves.
Kampot had my favourite bar and favourite burger place in Cambodia. 'Oh Neils' the Irish bar has great music and the Burger Shack is cheap and excellent and has a MacDonalds sign outside which is pretty funny.
Kampot to Koh Rong Samleom
Mad Monkeys booked this for us with Kep Travel. The journey was fine, it's not too long, bus, shuttle bus, boat... it's only about a three hour journey in total.
Koh Rong Samleom
We initially stayed at Dragonfly in M'Pai Bay, also known as 'The Village'. The Village was great, there was still lots of Cambodian life happening, kids, schools and midnight beach cows.
The Dragonfly dorm was nice enough, single beds, mosy nets, did get a bit hot. The bar there was fun, it has a good spot for watching the sunset (you'll need to get someone to show you). Have a look what you think, there's also an Easy Tiger there which is next to Dragonfly and highly recommended.
***WARNING*** There are no proper showers in M'Pai and lots of signs saying to save water. There's also no ATMs. They also hate it if you take $100 bills so try and break big notes.
We did the walk from M'Pai to Driftwood which takes about an hour, along beaches and through the jungle. Wear decent shoes. That was fun. Driftwood was cute (and vegetarian Esther!) And we could get a boat back for $5 each.
There was also a boat tour with snorkelling with a guy called Clayton who hangs out in the town in the morning before the tour leaves at 11.30. This was a brilliant day.
For our last night we moved to Saracen Bay to a hostel that was possibly called Yuvo??? I can't really recommend it. Saracen Bay's beach is much nicer and very resorty, fun for a night as there was also a party at Blue Dog hostel.
Koh Ring Samleom to Phnom Phen
We got the boat back to Sihkanouvile (which looked a bit dull) and, because the boat was an hour and a half late, just made our Giant Ibis bus to Phnom Phen. That bus was long but pleasant. If you're short of money try and go to an ATM before you get on board as it stops at quite a pricey restaurant half way.
Phnom Phen
We stayed at the Mad Monkey again, again in a private room ($15). It was directly above the bar so super noisy until midnight. They do have a quiet side though so you could maybe request that. Despite my deep distrust of Mad Monkey pub crawls we went on theirs and it was really fun.
Activities-wise we did S21 (the prison camp) which was horrific and then the Killing Fields (which was also horrific). This is the best order to visit them in. I think the tuk cost us $18 for the day. These are heartbreaking attractions but must-dos. Just prepare yourself for the horror and take some tissues.
... there we go! Hope that is helpful. .
Have a great time!
Xxx