Langkawi SkyCab and Sky Bridge. The steepest cable car ride of its kind climbs Mount Machinchang for views over the Andaman Sea. Around RM 85 ($21) for foreign adults including the SkyDome and SkyRex side attractions, plus a small fee of about RM 6 ($1.50) for the curved Sky Bridge at the top. Go before 11am — clouds and queues build after lunch.
Island hopping tour. A shared boat covers Pulau Dayang Bunting (Lake of the Pregnant Maiden), eagle watching and Beras Basah beach in about 4 hours. Group tours cost roughly RM 35-50 ($9-$12) per person — one of the cheapest island tours in the region.
Kilim Karst Geoforest mangrove tour. A boat ride through mangroves, bat caves and floating fish farms. More nature, fewer crowds than island hopping. Choose this if you have done beach-hopping trips elsewhere.
Pantai Cenang. The main beach strip — sunsets, parasailing, jet skis and rows of restaurants. This is the best area to stay for first-timers.
Underwater World Langkawi. A decent aquarium with penguins at the south end of Cenang. Keep it as a backup plan for a rainy afternoon; skip it on a short trip.
Duty-free shopping in Kuah. Chocolates, perfumes and alcohol at some of the lowest prices in the region. Stock up on the last day so you're not carrying bags around.