Use three weeks for the north and one connected coastal region
For a Thailand itinerary of 3 weeks, spend four nights in Bangkok, five in Chiang Mai, four in Ao Nang and six on Koh Lanta, then return to Bangkok for the final night. This gives you northern sightseeing and an extended island stay without crossing between the Andaman and the southern Gulf. Day 21 is departure day.
The plan assumes 21 calendar days and 20 nights inside Thailand, arriving and departing through Bangkok. It is an editorial route, not a package or a promise that a particular flight combination operates. Check the dated interregional journeys before fixing rooms. If your three weeks include long-haul travel outside Thailand, reduce the night ledger to match your actual arrival.
Where the 20 nights go
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| Your decision | Hotel nights | Full days between moves |
|---|---|---|
| Bangkok at the start | Nights 1–4: four | Days 2–4: three |
| Chiang Mai | Nights 5–9: five | Days 6–9: four |
| Ao Nang, Krabi | Nights 10–13: four | Days 11–13: three |
| Koh Lanta | Nights 14–19: six | Days 15–19: five |
| Bangkok before departure | Night 20: one | Departure on day 21; no extra sightseeing day promised |
Days 1–4: Bangkok, with Ayutthaya as a return day trip
Day 1: arrive in Bangkok, reach the hotel and eat nearby. Keep the evening free of non-refundable plans. Sleep in Bangkok.
Day 2: visit the Grand Palace and Wat Phra Kaew as the main morning stop; add Wat Pho if you want another temple, or keep the afternoon by the river. Use the Bangkok guide for visitor rules before leaving the hotel. Sleep in Bangkok.
Day 3: give Chinatown and a separate river or neighbourhood outing their own day. This avoids treating all of Bangkok as a temple circuit around the palace. Sleep in Bangkok.
Day 4: make Ayutthaya a return day trip, or keep another Bangkok day if ruins are not a priority. Keep your Bangkok room and leave the main luggage there. Sleep in Bangkok for the fourth night.
Days 5–7: reach Chiang Mai, then separate city and mountain visits
Day 5: travel to Chiang Mai on your booked journey, transfer to the hotel and leave the rest of the day light. This hotel-based ledger assumes you sleep in Chiang Mai that night. An overnight train needs a revised calendar because it replaces a hotel night.
Day 6: group Wat Phra Sing and Wat Chedi Luang with the old-city streets and a long lunch. Sleep in Chiang Mai.
Day 7: make Doi Suthep the main outing, then return to the city rather than adding a second distant mountain destination. Sleep in Chiang Mai. These stops give the northern block a different purpose from the beach stay that follows.
TAT: Chiang Mai temples, Doi Suthep and separate mountain destinationsDays 8–9: one dedicated outing and a flexible Chiang Mai day
Day 8: choose Doi Inthanon as a full road-based mountain outing if the journey appeals. Select the available stops and do not assume a seasonal walking trail has reopened. If you prefer a city day, use Nimmanhaemin for food and shops instead. Sleep in Chiang Mai.
Day 9: keep the last full northern day movable for weather, more old-city time or an outing postponed from day 8. A walking street must fit its actual operating day. Sleep in Chiang Mai for the fifth night.
Chiang Rai and Pai are omitted, not squeezed into spare evenings. If either is central to your trip, replace part of this block and remove a coastal base rather than keeping every hotel move. Review the northern timing guide for haze and air-quality considerations before booking outdoor-heavy days.
TAT: Doi Inthanon and Nimmanhaemin as distinct outing choicesDays 10–13: Ao Nang, Railay and one optional island excursion
Day 10: use your booked journey to Krabi, then transfer by road to Ao Nang. Choose a workable direct flight if available for the date; if your tickets require a connection, keep the whole day for that journey. Do not book an afternoon boat tour against an unspecified arrival. Sleep in Ao Nang.
Day 11: stay around Ao Nang and settle into the coastal part of the trip. Your hotel is on the mainland; a boat is not part of every arrival or evening meal. Sleep in Ao Nang.
Day 12: visit Railay as a return boat outing when conditions and services allow. Keep the Ao Nang room and leave luggage there. If the crossing cannot operate, swap this with day 13. Sleep in Ao Nang.
Day 13: choose one island excursion, such as Hong Islands or the Four Islands, or leave another beach day free. These are different routes with different stops and possible admission exclusions. Sleep in Ao Nang for the fourth night.
TAT: Ao Nang facilities and boat excursionsDays 14–16: transfer to Koh Lanta and settle at one beach
Day 14: move from Ao Nang to your Koh Lanta hotel using a booked transfer with the full endpoint included. Compare the road-and-vehicle-ferry option with any passenger-boat alternative actually operating on your date. A pier-only fare is not a hotel-to-hotel transfer. Sleep on Koh Lanta.
Day 15: spend the first full day around the chosen beach. Pick Klong Dao or Long Beach if those fit your stay-area preferences; do not change hotels merely to try another beach. Sleep on Koh Lanta.
Day 16: arrange a separate visit to Lanta Old Town on the east coast, returning to the same beach hotel. TAT distinguishes the Old Town from the arrival and services area at Saladan. Sleep on Koh Lanta.
TAT: Koh Lanta beach geography, Saladan and Lanta Old TownDays 17–19: keep enough island time after the transfer
Day 17: keep a full beach day, choosing swimming according to local flags and conditions. Sleep on Koh Lanta.
Day 18: choose an optional boat excursion only when the route is open and operating, or spend another land-based day on the island. Koh Rok and Koh Haa are not guaranteed year-round additions: TAT describes seasonal closures among the smaller national-park islands, and a general season guide does not confirm a particular reopening. Sleep on Koh Lanta.
Day 19: leave the last full island day uncommitted for rest or a postponed outing. Confirm tomorrow's complete airport transfer rather than moving to another island for a final night. Sleep on Koh Lanta for the sixth night.
Six nights provide five full days after arrival. They are a deliberate allocation for a settled stay, not six days that need six paid excursions.
TAT: Koh Lanta geography and typical small-island monsoon closuresDays 20–21: return to Bangkok before the international departure
Day 20: take the pre-arranged transfer from your Koh Lanta hotel to Krabi Airport, then the booked flight to Bangkok. Work backward from the airline's check-in deadline and include the road journey, ferry queue where applicable and disruption margin. Sleep in Bangkok near the area or airport appropriate to tomorrow's departure.
Day 21: depart Thailand. This is the end of the 20-night ledger; no Thailand hotel night is counted after departure. A Bangkok buffer reduces reliance on an island transfer on the day of the long-haul flight, but it cannot guarantee against every disruption.
If your international ticket departs directly from Krabi, you can remove the Bangkok flight and redesign the final stay around that airport. Do not treat a different arrival and departure airport as automatically cheaper or leave the island-to-airport transfer out of its cost.
Change the coast when the month or travel style calls for it
This printed route is Andaman-led. TAT's regional weather guide places the Andaman's stormier monsoon period broadly in April–October, while the southern Gulf islands around Samui receive their heaviest rain broadly in September–December. A July or August trip therefore deserves a Samui comparison; a November trip does not make the Gulf an automatic weather fallback. These are climate patterns, not forecasts.
For a simpler three-week trip, keep days 1–9 and replace days 10–19 with ten nights in a single Samui or Ao Nang base, then retain the final Bangkok night. That removes the day-14 hotel move and gives nine full days at the coast. Use those days for local outings and rest; a second island is optional. Book the revised flight and hotel transfer explicitly.
Do not add eastern Thailand's Trat islands to this southern circuit just because they are also in the Gulf of Thailand. They use different gateways and have their own weather and boat-service patterns.
TAT Malaysia: regional monsoon differences; not a dated forecastWhat to put in the three-week budget
Price 20 accommodation nights at the real dates and room type, the Bangkok–Chiang Mai journey, Chiang Mai–Krabi journey, Ao Nang–Koh Lanta transfer, Koh Lanta–Krabi Airport transfer and Krabi–Bangkok flight. Add airport transfers not included in those tickets, meals, local transport and the excursions you actually choose.
Compare baggage and cancellation terms before buying the cheapest flight. For boats and tours, separate the fare from park admissions, hotel pickup and any equipment exclusions. An overnight train changes both the accommodation count and the following day; it is not an extra free day on top of this route. No fixed trip total is quoted without dates, party size and the actual booking basket.