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.
Kuantan is the largest city of the East Coast of Peninsular Malaysia with a population of about half a million. It is also the capital of the state of Pahang.
Kuantan is located about halfway between Singapore (to the south) and Kota Bahru (to the north). The city is situated at the coast of the South China Sea near the mouth of the Kuantan River. The city is not a major tourist destination, rather a stopover point for island destinations (Tioman, Redang, Perhentians, etc.) along the East Coast. From Kuantan you can also also reach the popular beach in Cherating in less than an hour with the local Bus.