Capital: Bangkok
Formerly the Kingdom of Siam. I love Thai food probably the most of any asian food. Pad Thai, papaya salad, mango sticky rice, tom yum soup...no wonder I enjoyed the country.
Pro Tip: During my visit, I was allowed two entries in a year. This worked for my combo trip to Vietnam, Laos, and Cambodia.
Bangkok: Capital city. Royal Palace. Street food. Night life.
Chiang Mai: A small town but lots of history, an opportunity for the Elephant Jungle Sanctuary (also available from Phuket, Pattaya, and Samui), and a great night market within the walls of the Old City.
Chiang Rai: Another small town with the Blue Temple and White Temple as the main attractions.
Phuket: A beach town with room to lay low while enjoying the sand and surf and lots to do if you want to be busy in Old Town.