Start with 2 nights in Bangkok; use your first night to recover from your flight and go visit Koh San Road (maybe see a ping pong show if you’re not shattered)
Head early so you get the full day in Hua Hin: you can go visit the amazing elephant sanctuary that allows you to walk, feed and wash the elephants (no riding here!)
Koh Samui is a beautiful island and you get there via bus and boat from Hua Hin.
Koh Phangan is well worth a spot on any Thailand itinerary for one reason … the Full Moon Party!
Koh Tao, best known for its snorkelling and beautiful beaches, is the smallest of the islands in this region and is well worth a night's stay
Phi Phi is a small island, now best known for partying.
You can also visit other islands off Phi Phi, so 2 nights is good if you want a day for recovering then an actual day of sightseeing
Other than Patong Beach, Phuket is actually quite a dire place to visit.
A strip called Bangla Road, which is like the party capital/weird sex capital/ ping pong/sex show capital of the area.
If you want cheap shots, then there we go!
Chiang Rai is home to some of the best temples anywhere in Thailand, and probably Asia (in my opinion).
The White Temple is iconic architecture, and absolutely beautiful, and the blue temple is peaceful, stunning and, best of all, free
Pai is in the far north of Thailand, and you can get there by only one road.
So you’ll need to either rent a moped and drive these winding roads yourself, or you get a little mini bus from the Arcade Chiang Mai bus station for 150 baht