The ideal trip around Thailand is Bangkok, Chiang Mai, and some south beaches, but there is a problem, and the problem is the distance between these places. From north to south there are 1600 km.
The perfect trip has to las at least 2-3 weeks because you probably have to take a plane to move around the country
We can start in the capital of the country, Bangkok. The best option is to be at least 2-3 days visiting each city, if you stay more days you can visit Ayutthaya, the old capital of the country, or some floating market.
The next destination could be Chiang Mai the capital of the north, you can travel by train in the Hua Lamphong train station. We recommend to take a night train to save the money for that night and you don’t waste time on the route. These trains cost about 15 € and spend between 13-16 hours to arrive.
In Chiang Mai the people normally stay there about 4 days visiting the city and its surrounding. One place to visit is Doi Inthanon national park, there they ride an elephant and takes massages because they are cheaper and famous.
The next destination could be Krabi in the south, there aren’t direct flights so you have to fly to Phuket or Hat Yai and then, by bus.
Krabi is a city in the south, near the beach. In Krabi we recommend a Songtaew to the cost town Ao Nang where there are accommodations and you can do boat trips.
One of the places you have to go is Railay, you only can access by boat.
After 3 days in Krabi, you can take a bus to the north, to Suratthani. It is not an interesting city but you can take a boat to go to the gulf islands
Then you can go back to Bangkok by plane or bus and buy the last shopping