Langkawi is an archipelago of 99 islands in the Andaman Sea, some 30 km off the mainland coast of northwestern Malaysia. The islands are a part of Malaysia’s Kedah state, but are adjacent to the Thai border. By far the largest of the islands is the eponymous Pulau Langkawi with a population of about 45,000. The island is a declared duty-free zone.
The peak season is from December to March when moonson at the eastcoast shuts down most of the Islands there (Perhentian etc.). This makes Langkawi a good island alternative during that time period. Generally though, Langkawi can be visited all year around.
Cherating is the only real backpacker hub at the east coast of the peninsula on the mainland. Offering plenty of affordable chalets and a relaxed atmosphere, it is good place to stop for a night or two on the way up or down the east coast. The beach itself is not that spectacular and misses the palm directly at the beach. But it has a good vibe and few things you can do like taking a tour or renting a kayak up the river into the mangroves. There is also an active surfer scene when the waves are right. Cherating is located about 30km or 1h by local bus north of Kuantan.