Koh Samui or Penang?

On Koh Samui the beach is the whole point. Chaweng is a long sweep of fine white sand with clear water, Lamai is a slightly rougher version just to the south, and Choeng Mon and the north coast bays offer gentler swimming. Rocky coves such as Silver Beach are lovely for a swim among the boulders.

Penang treats the beach as a side trip. Batu Ferringhi is a resort strip of jet skis and parasailing, but the sea there is often murky. The better sand at Monkey Beach and Kerachut in the national park is a hike or a boat ride away and has few facilities.

Penang is the island you plan your meals around. Its hawker centres and old coffee shops serve Hokkien, Teochew, Malay, Tamil and Nyonya dishes side by side, and there are banana-leaf meals in Little India and night stalls on Gurney Drive.

Samui eats well in a narrower way, with southern Thai curries, beach-grilled seafood and the night markets at Lamai, Maenam and Fisherman's Village. Beyond Thai cooking and grilled fish there is little variety, and the menus on the Chaweng strip are uneven.

George Town is a true heritage destination: two centuries of trading-port shophouses, clan temples, stilt villages on the water, and churches, mosques and Hindu and Chinese temples sharing Harmony Street. Kek Lok Si on the hill outside town adds one of the largest Buddhist temples in Southeast Asia.

Samui's sights fit into a single morning loop: the Big Buddha on its causeway islet, the many-armed Guanyin at Wat Plai Laem, the mummified monk at Wat Khunaram and the old wooden shophouses of Bophut. Anyone who comes for heritage will run out of things to see quickly.

Samui is where you go to party. Chaweng's beach clubs, roadside bars and the clubs in the lanes behind the sand run late through the high season, with DJs and fire shows. The full moon parties on Koh Phangan are a short boat ride away, although parts of the scene are generic and seedy.

Evenings in Penang are gentler: backpacker bars around Love Lane and Chulia Street, cocktail bars in restored shophouses and a few clubs on Upper Penang Road. Many nights end over a late plate at a hawker centre instead.

Both islands offer plenty of green and blue, but in different ways. Samui's best scenery lies at sea. Boat trips go to the forty-odd limestone islands of Ang Thong for kayaking, snorkelling and the emerald lake, and divers go north to Sail Rock and Koh Tao. On the island itself there are only modest hills and the Na Muang waterfalls.

Penang's strengths are on land. You can take the funicular or walk the jungle trails up Penang Hill to a cooler summit and a canopy walk. There are also forest paths to a lighthouse and turtle beaches in the national park, and quiet cycling country among the orchards of Balik Pulau.

From Penang, a day out can take you into mainland Malaysian history. Ipoh, about two hours south by train, has a colonial old town and cave temples in limestone hills, and Taiping, royal Kuala Kangsar and the early temple ruins of the Bujang Valley are all within reach.

Samui's outings are island-hopping instead: Koh Phangan's quieter beaches and port town, or a full day out to Koh Tao and the sandbar islets of Koh Nang Yuan. The nearby mainland is only a transport hub, so there are no historic towns to visit.

For a family beach stay, Samui is at least as good a base and usually the easier one. Choeng Mon, Bophut and Maenam have shallow, calm water, and many resorts are built around children, with large pools and kids' clubs. Older children can take a boat trip to Ang Thong. Otherwise there are only a few animal parks and a water park, and you should keep away from Chaweng's late nights.

Penang has the weaker sea but a wider spread of outings. Families tend to stay at Batu Ferringhi and use the resort pool, then go to the water theme park and butterfly park at Teluk Bahang, ride the funicular up Penang Hill and watch the macaques in the Botanic Gardens. The hawker food is easy to share, but George Town's stepped walkways are hard going with a pushchair.

Penang is the easier island to get around without your own wheels. The heritage core of George Town can be walked or covered by trishaw and bicycle, buses run out to Batu Ferringhi, and ride-hailing is cheap for anything farther away. The mainland railway is a short ferry ride away at Butterworth.

On Samui, everything hangs off a 51km ring road. Songthaews run along it with no timetable, taxi fares are haggled and expensive, and many visitors end up on scooters on hilly roads where accidents are common. Each beach area is walkable, but walking between them is not practical.

Neither island is a shopping destination, but Penang has more worth taking home. George Town's antique and curio shops, its studios of Peranakan beadwork and batik, the fabrics and gold of Little India and the nutmeg at Chowrasta market are more interesting than anything you can buy on Samui.

Samui's best browse is the Friday walking street in Fisherman's Village, with crafts and coconut-wood homeware. Otherwise it is beachwear, tailored suits, the Chaweng mall and stalls selling copies.

Penang is easier on the wallet. Hawker meals and rides across town cost very little, guesthouses and mid-range hotels in George Town are modestly priced, and most temples and clan houses are free or cheap to enter. Alcohol is the exception, as tax makes drinks cost far more than food.

Samui is among Thailand's dearest destinations. Its resorts are priced for international visitors, taxis are expensive and flights to the small airport are limited. Bungalows away from the beach, night-market food and massages keep a careful trip affordable, especially on the north and west coasts.

Neither island is a place to travel for the stage, but Samui offers less. Its shows are put on for visitors: Muay Thai fight nights around Chaweng and Lamai, ladyboy cabaret, fire dancers on the beach and cover bands in the bars. There is no theatre or concert hall behind them.

Penang is the better choice for anyone who wants to see something performed, and much of what it offers grows out of its own traditions. For a few weeks each year the George Town Festival fills the heritage streets with theatre, dance and music. Temple festivals bring Chinese street opera and puppet shows on temporary stages, and a performing-arts centre on the north coast puts on local plays and concerts. Plan your visit around these occasions, because between them there is little to attend.

Samui is one of Asia's best-known places for a retreat. Lamai and the hills above it are known for detox and fasting programmes, and there are yoga and meditation centres and hillside spas looking over the Gulf. The quiet afternoons at Maenam, Bang Po and Lipa Noi suit a slow stay.

Penang's version of wellness is a daily foot reflexology session or a Chinese or Malay massage, a few resort spas at Batu Ferringhi and the cool air at the top of Penang Hill. These are pleasant breaks rather than a reason to choose the island.