Where to stay -
We stayed at one of the most popular 'resorts' and the one directly opposite the jetty from where the ferry drops you off - Coco's bungalows. There is a hillside of huts behind the bar area, absolute basics with walls of wicker, padlocked front doors and a mosquito net canopy over the beds. They're seriously cosy and the majority come with a bench and hammock on the balcony. We shared with one other guy that we met, to split the cost - they generally fill up quite fast too - we paid total $15 for one night, so it worked out at $5 each. For one of my favourite accommodations.
The Treehouse Bungalows further down the beach looked pretty awesome, they start at $35 and have me pining to go back for a couple of nights just to experience them.
The rest of your trip -
There's a real family feel for anyone that stays more than a couple of days, especially if you stick with the same resort. We spent a couple of days there which had the hours filled with sunbathing for the most part. During peak season, we heard the parties can get pretty insane, ours was a more chilled night, but still had time to dance.
The second day was a rainy one - with a storm around the corner - we spent the morning in the cute roof terrace of Coco's. You can look out over this side of the island and people watch, favourite. Dosing off on the window seat has its risks of rolling down the roof, it gets a touch too comfy.
There are dogs all over the island and while I am a massive dog person, my overly cautious fear of rabies had me develop a slight dog fear for the whole of our trip. We did befriend a puppy, Zoe, that one of the backpackers turned islander had adopted for daily walks along the beach. He swears it wasn't a pick up tool but I'm still not so sure.
The locals are insanely friendly - as are the entirety of Cambodia from what we saw, quite honestly some of the friendliest people I've ever met - don't be scared to ask pretty much anyone, for anything, they'll more than likely sort you out.
There isn't a tonne of activity on the island, but you can train for your diving license, or go out with the crew if you've already qualified. The locals and backpacker-turned-localers were in the midst of building a school when we there. From scratch. They love for anyone to get involved, it's all completely voluntary but is an amazing project while you've got the time. An easy tan, too, if that's what you're there for.
This place is where a torch will probably be utilised. Don't think a trip across the world will have me parting with my iPhone - it was a lifesaver. If you're staying at Coco's and not going to bed in daylight, the tracks up to the rooms are pretty exciting. Especially when there is $1 beer and a very 'large' bill involved. Don't even bother with anything more extravagant than flip flops or Converse. It's not going to work.
Despite it being rife with backpackers, there is absolutely zero commercialism here - there have been plans to put a proper resort onto the island, to capitalise on the amazing beauty that's there. I love that it still has a home grown feel and to me, that's why I liked it. Any real hotels and uniformed staff would completely take away the vibes of this island so I hope for any of you that visit in the future, you get the same out of Koh Rong as I did.
A word of advice -
Check the weather before you leave for your boat trip there and back. Our ride over wasn't all that rough, but there were quite a few people feeling the affects of seasickness.
The ride back, we went to the store to get travel sickness pills which apparently were amazing. It was a pretty dull day, but mid trip we saw the storm on the horizon. Just as we were coming into dock on Sihanoukville, there was a serious storm - I'm talking Day After Tomorrow vibes - lighting, thunder and severe rough seas. But, neither of us felt nauseous and we're both pretty prone to it. Check ahead and take some travel sickness pills on your trip as a safety measure.
Also, arrange travel to/from the jetty on the mainland with a hostel. The majority are all around the same area so you can avoid paying for a more expensive tuk tuk - especially when it's pitch black and you feel like you're doing some kind of army trial with your backpack.
Once again, the Living Doll travel blog managed to capture the island (and here) pretty well - she stayed in the same place we did.