Sihanoukville has two main beaches Serendipity and Otres which fall in complete opposite ends of the beach vibe spectrum: seedy, bass-bumping Serendipity Beach and chilled-out, hippy enclave Otres Beach. We undoubtedly had some wonderful nights out in Serendipity and also spent a day just lazing by the sea in Otres.
My advice for Sihanoukville is just take it for what it is. It’s a seedy party town on a beach. If you’re looking for nightlife, head to Serendipity, and if you want to chill out, choose Otres.