Aitutaki or Rarotonga?

Aitutaki has the finer lagoon. It is a wide triangle of turquoise water ringed by motu, and its best sand is out at Tapuaetai and around Honeymoon Island, reached by cruise or kayak and usually empty. Closer in, Ootu and Amuri are pleasant, though low tide can leave very shallow water over coral rubble.

Rarotonga's strength is that its beaches go almost all the way round the island. Muri has calm water and its own small motu, and the south coast around Titikaveka and the Aroa reserve gives the best snorkelling straight from the sand. The north and west coasts are rockier, and the reef passages have dangerous currents.

Both islands offer ika mata, umu-baked food and good fresh fish, but Rarotonga gives you more ways to eat them. The Saturday Punanga Nui market in Avarua and the Muri night market have stalls cooking local dishes, and there are beach cafés, decent coffee and a beer brewed on the island.

On Aitutaki you mostly eat in resort dining rooms, at a few cafés and at takeaways in Arutanga. The island night buffet is the main chance to try traditional food, and over a week the menus start to repeat.

Neither island is a sightseeing destination, and on both the living village culture matters more than any monument. Rarotonga has a little more to visit: a small national museum and a library-museum in Avarua, the coral-lime Cook Islands Christian Church and the marae of Arai-te-Tonga, easy to find off the inland road.

Aitutaki's church in Arutanga is older, dating from the 1820s, with carved interiors from the missionary era. Its marae lie unmarked in the bush and are best found with a local guide.

Rarotonga has the only real night out of the two. On Fridays Avarua's waterfront bars fill up and a couple of places with dancing stay open late, though on other nights it is a beach bar or resort lounge at most. Aitutaki is quieter still, with sunset drinks, the weekly island nights and very little after dinner.

The outdoors is just as good on both islands, but in different settings. Aitutaki's is almost entirely on the water. You can snorkel over giant clams, swim with turtles and trevally, and kitesurf the southern lagoon in the trade-wind months. Its shallow flats draw fly fishers after bonefish. On land there is only the short climb up Maungapu, at about 124m, for the view.

Rarotonga adds a steep, forested volcanic interior. The cross-island track passes beneath the Needle and a waterfall, and harder ridge walks such as Ikurangi need a guide. From July to October humpback whales can often be seen from the shore.

Aitutaki offers no day out beyond its own lagoon. The cruise to the motu is its great excursion, but it shows you more water and sand rather than somewhere new, and Rarotonga is too far to see properly in a day.

Rarotonga has the one outing that really counts: a flight of under an hour to Aitutaki for a lagoon cruise and lunch on a sandbar, back the same evening. Apart from that, a day out means going round the island itself, because the other southern islands need overnight stays.

Rarotonga is the easier island with children. Many resorts have kids' clubs and family units, the sheltered water at Muri and on the south coast suits small swimmers, and glass-bottom boats and the markets help fill the days.

Aitutaki's lagoon is just as gentle, with fish visible from the shore. However, several resorts take adults only, there is nothing to do beyond the water, children need reef shoes for the coral, and the connecting flight makes a long journey longer.

Rarotonga has a working bus. It runs clockwise and anticlockwise round the 32km coast road and stops wherever you flag it down, though it thins out in the evenings and on Sundays. Avarua and Muri are each walkable on foot.

Aitutaki is smaller but has no bus to speak of, and the gaps between guesthouses and Arutanga are too far to walk in the heat. You will need a scooter or bicycle, and a boat or kayak to reach the motu.

For souvenirs, Rarotonga is the better stop. Avarua has specialist black pearl shops, a short street of boutiques and gift shops, and the Punanga Nui market for tivaevae quilts, carvings and pandanus hats. Aitutaki has only general stores and a few craft stalls in Arutanga, so anyone who wants pearls or crafts should shop on Rarotonga.

Both islands are expensive because so much is imported, but Aitutaki costs more. Its overwater and beachfront bungalows are at the top of the market, meals and groceries cost more again, and the connecting flight, cruises and fishing guides add up. Guesthouses with kitchens are the main way to save.

Rarotonga gives budget travellers more options. It has backpacker lodges, self-catering units, market food and the island bus, and its hiking trails and lagoon are free.

Cook Islands drumming and dance is worth seeing on either island, and Aitutaki's dancers are especially well known. On Aitutaki, though, it comes mainly as resort dinner shows. Rarotonga has island nights several evenings a week at both resorts and cultural venues, and around early August it hosts Te Maeva Nui, when teams from every island compete in dance and chant. Both have Sunday hymn singing that is well worth hearing.

On both islands relaxation comes mostly from the slow pace rather than from spa treatments, and neither has a bathing tradition. Aitutaki is the stiller of the two. Hammocks hang over the water, Sundays come to almost a complete halt, and the larger resorts have treatment rooms facing the lagoon.

Rarotonga has a bit more on offer outside the resorts, with day spas and beach yoga, and its south and east coasts around Muri and Titikaveka are the calmest places to stay.