DEFINITELY check out the Queen’s Elephant Conservatory, not too far from Chang Mai. It’s very educational, all your money goes to helping preserve the animals that once were used for work and now are being replaced by machines.
Take a cooking class in Chang Mai.
Go scuba diving around Krabi.
Rent a scooter and drive around in the hillsides, checking out the smaller, non-touristy towns.
Take the train.
Go to the Thai Massage school in Bangkok where any kind of massage is discounted by the practicing students.
Talk to some monks-in-training, they will love the opportunity to practice their English, and you will love learning more about their culture.
Eat fresh pad thai and pineapple from the street vendors for like 50 cents. AND mango coconut sticky rice, ohhhhh….
If you get “creature comfort” sick, check out a VIP movie in Bangkok – new releases with reclining leather couches, pillows, blankets, and table service for the price of a regular movie in the states.
Consider hopping over to Cambodia and checking out Angkor Wat for a few days – phenomenal!