Tip · Decide the month before anything else. The Andaman and Gulf coasts have opposite rainy seasons, and the north has a smoke season from late February to April, so the calendar rules out half the map for you.
Most Thailand itineraries try to cover far too much of the country.
I understand why. The flights are long, you might only come once, and the map is full of names you've heard of. So people land with a plan that hits Bangkok, Chiang Mai, Pai, Phuket, Phi Phi and Koh Samui in twelve days, and they spend most of it on the way somewhere. I lived in Thailand for years and I've planned this trip for enough visiting friends to have a fairly fixed way of doing it. This is that method, in the order I'd actually do it. It's just how I go about it, and your taste might differ, but it has held up pretty well.
Pick the month before you pick the places
Thailand doesn't have one climate, it has about three, and they don't line up. The Andaman side (Phuket, Krabi, Koh Lanta) is dry from roughly November to April and wet the rest of the year. The Gulf side (Koh Samui, Koh Phangan, Koh Tao) runs the other way, with its wettest stretch from October to January, right when the rest of the country is at its best. The north has its own problem: from late February to April farmers burn the fields, and Chiang Mai sits in a bowl that holds the smoke. In a bad March you can't see Doi Suthep from the city.
So the month decides half the map for you. November to February works almost everywhere except the Gulf islands, which is why it's peak season and why everything costs more. June to September is wet on the Andaman side and fine on the Gulf. March and April are hot everywhere and hazy in the north, though Songkran in the middle of April is worth being here for if you don't mind being soaked for three days.
I wouldn't let rainy season put you off. On most days it rains hard for an hour or two in the afternoon and then clears, and the country is half empty and noticeably cheaper. If my only choice was a trip in August or no trip, I'd take August every time. Our month-by-month guide goes into detail, and each month has its own page if you already know your dates, like Thailand in November.
Two places, maybe three
Once you know the month, the next decision is how many places, and my answer is fewer than you're planning. Every time you change base you lose most of a day: checking out, getting to the airport or station, the trip itself, finding the new hotel, working out where to eat. Do that six times in two weeks and you've spent a third of your holiday in transit.
My rule of thumb is Bangkok plus one region if you've got under ten days, and Bangkok plus two regions for anything longer, up until about three weeks, which is the first point where doing the north and the south both starts to make sense without rushing. The three regions, in the sense that matters for planning, are the north (Chiang Mai and around), the Andaman coast (Phuket, Krabi, Koh Lanta) and the Gulf (Samui, Phangan, Tao). Within a region, stay put. Chiang Mai is a base, not a stop, and the day trips from it are better than the towns three hours further on. Trying to do Chiang Mai, Pai and Chiang Rai in a single week is how you lose the time you came for. Pai is the usual example: it's a pretty valley that is now extremely touristy, and if I wanted a second northern stop I'd choose Chiang Rai over it.
Between the two coasts, I'd pick on weather first and character second. The Andaman side has the scenery, the limestone cliffs and clear water, and Krabi with Railay is the version of that I'd send most people to. The Gulf islands are easier, cheaper for diving and better in the months when the Andaman is wet.
Bangkok first, and give it three nights
I'd always start in Bangkok rather than end there. You'll land jet-lagged, you need a SIM card and some cash, and Bangkok is the easiest place in the country to sort all of that in an afternoon. Three nights is about the least I'd give it on a first visit. Two feels rushed, and a week is more than most people want of a very big, very hot city on their first go.
Stay within walking distance of a BTS or MRT station. That matters more than which neighbourhood, because Bangkok traffic turns a twenty-minute hop into an hour, and the trains don't care. I usually put friends in Silom or around the lower Sukhumvit sois; the neighbourhood guide walks through the trade-offs.
Once you're there, I'd spend one of the days on the route I give friends, a morning market, a river boat, Talad Noi and Wat Arun, and one evening at a proper night market rather than the ones near the hotels.
What I'd leave out: the floating markets. Damnoen Saduak and Amphawa are two hours out of town, and what you get at the end is a boat queue and a souvenir stall on water. I've written about Bangkok without the tourist traps if you want the longer list.
One thing to check twice: Bangkok has two airports, Suvarnabhumi (BKK) and Don Mueang (DMK), 40 km apart, and the budget airlines mostly use the second one. Look at which airport your domestic flight leaves from before you book a hotel near the wrong one. The airports guide covers both.
Book the transport yourself
The travel agencies on the tourist streets will happily sell you a bundle, and it's nearly always the wrong bundle at the wrong price. Everything between cities in Thailand is easy to book on your own phone, and doing it yourself means you pick the departure time rather than the one that suits the minibus operator.
For Bangkok to Chiang Mai I'd take the overnight train if you have the evening to spare. It leaves from Krung Thep Aphiwat station, takes about 12–13 hours, and you save a night of hotel. The second class sleeper with air conditioning is comfortable enough; book a lower berth, it's wider, and expect to pay around 900–1,000 baht for it. The one catch is that berths go on sale about three months before departure and the popular trains sell out, so this is the single thing I'd book early even while leaving the hotels open. If you'd rather not, it's an hour and a quarter on a plane and there are flights every hour or so.
Chiang Mai to the south is a flight, not a train: about two hours direct to Phuket, and there are direct Krabi flights too, though fewer of them and I haven't flown that one myself. Bangkok to Krabi or Phuket is about an hour and twenty minutes, and if you book a few weeks out the fare is often 1,000–2,000 baht, cheaper than the hotel you'll sleep in that night.
For buses, ferries and the train I use 12Go, which lets you see every operator on a route and pay by card. For flights I go straight to the airline: AirAsia and Nok Air for most routes, Bangkok Airways if you want to fly into Samui, since they own the airport there. Ferries to the Gulf islands don't need booking ahead outside peak season. The transportation guide has the full picture, including how the trains work.
Book the rooms, but keep them cancellable
I book the Bangkok hotel and a room at each new stop before I leave, but I make sure every one is cancellable for free. That gives you a bed waiting after each flight and still leaves you free to change your mind: switch to a better deal if you find one on the ground, or stay an extra couple of nights somewhere you like, which happens more often than you'd think. In peak season on the beaches, Railay and Koh Lanta between mid-December and mid-January, I'd lock those in early, because the good-value rooms go first even if you can still cancel them later.
For comparing rooms I use Agoda, which tends to have better rates in Thailand than the bigger international sites, and I filter for free cancellation before I book anything. There's more in the hotels guide on what a fair price looks like in each place.
Leave the days mostly empty
The last thing I'd do is plan every day. Book the one or two things that need booking, a cooking class in Chiang Mai, a longtail to the Hong Islands, a dive course on Koh Tao, and leave the rest. The best parts of my own trips have been the days when nothing was scheduled and we followed a market or a recommendation from someone at the guesthouse. A trip with every hour accounted for is going to feel like work by day five, and your itinerary will fall apart at the first rainstorm anyway.
What a two-week version looks like
Putting the above together for a first trip in, say, November: three nights in Bangkok near a BTS station, the overnight train to Chiang Mai, four nights there with one day trip to Doi Inthanon, a flight south, four nights around Krabi with two of them at Railay, and a flight home from Krabi or Phuket. That is roughly the route in our classic two-week itinerary, which you can open and adjust. If your dates or your taste are different, the trip planner will show you the weather verdict for each region on the days you've got and let you build your own.
Swap Krabi for Koh Samui if your dates are between June and September. Drop Chiang Mai altogether if it's March, and add a second beach instead.
Before you land
The rest is small and mostly sorted on the plane: which airport, a SIM or eSIM, enough baht for the first day, and a handful of apps. I've kept that to a first-trip checklist so you don't have to remember it. Two things from it worth repeating here: buy your SIM from a 7-Eleven or the carrier's app rather than the airport counter, and don't exchange much money at the airport, because the rates in the city are noticeably better. The SIM card and money guides cover both.
So the whole method is to pick the month, keep it to two or three places, start in Bangkok, book the transport yourself and book rooms you can still cancel. If a friend gave me two weeks and asked me to plan it, that's the trip I'd hand back, and it's the one I'd take myself.
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