A trip to Cambodia with the same friend I had visited Vietnam with the first time came about after optimistic plans for Turkey fell through. Direct flights not available, we flew in via long layovers in Bangkok and Kuala Lumpur reaching there between late morning and early afternoon.
With a full night of travel, the priority was shower, lunch and sleep as soon as we checked into our hostel. The hostel we stayed at was named Onederz and it has pretty much become my favorite hostel so far. Obsessively clean, something for all personality-types, spacious and an all-night bar.
Piece of advice - everyone speaks English and uses USDs so don't even worry about. Do worry about getting overcharged by tuktuk drivers. Have the hostel send someone to pick you up from the airport.
Waking up late in the evening we went over to Pub street, found a place to exchange a couple of damaged dollar notes and found a place with live music and cheap beer to pass the time