Thailand is awesome! You need to spend a few weeks minimum because there are lots of places to go and things to see!
You will see a lot of Budda statues and temples. You can’t avoid it, they are everywhere. The word “Buddha” brings an image of a laughing bald man with a gigantic belly, but this is not the Budda you will see ever.
There are lots of different locations to visit in Thailand, and every single one is unique.
Go to The Full Moon Party! You much do this. It happens once a month on the saturday closest to the full moon. Even if you hate this kind of stuff you need to go for the experiance. It is basically “Mardi Gras, Burning Man and Spring Break all rolled into one party on a beach with no rules! I have stories if you want to know more. But you should go just to experience the chaos for yourself.
Play with elephants! Don’t ride them! There are a bunch of elephant sanctuaries that you can visit that take good care of elephants. the places that you see where you can ride them are very inhumane and they treat the animals poorly. You can have an wonderful elephant visit without riding on top of them. Most of the sanctuaries offer options to bath with the elephants in the water and that is way more fun then a ride any day!
Go to Chang Mai! It’s awesome, lots to see in town and there are a bunch of great day trips in the area. In the northern mountains is an awesome town not far from Chang Mei called Pai. You should rent a motorcycle or catch a ride up there. Its an awesome old hippy town and you will love it! There is great hiking and more.
See the Black temple and White temples. They are both amazing and very different from each other. Another easy day trip from Chang Mai.
Go shopping at the Chatuchak Market in Bangkok. Put aside a while day for this. It’s a HUGE football field sized market that sells literally anything you can imagine. Everything is made in Asia so you will find everything. It is sectioned by type and I suggest trying to get through as much as you can in one day. You won’t see it all obviously, but the deals are amazing and you can buy all your souvenirs and you next years wardrobe here.