Are Koh Rong and Koh Rong Sanloem worth the detour?
The islands can be worth it if beach time is the point, but they are not friction-free add-ons. Ferries, weather, cleanliness, nightlife mood and development all decide whether the detour feels restful or annoying.
Answer
Go to Koh Rong or Koh Rong Sanloem because you want island time, not because the itinerary needs a beach box ticked. The best version is simple: enough nights, realistic ferry expectations, a carefully chosen beach or village, and acceptance that weather can rewrite the plan. The weaker version is one rushed night after a long road day, followed by another transfer. Cambodia’s islands can give the trip a soft ending, but only when the detour has room to behave like an island detour.