I know what is it for because I used last year when I was in the country on COE. It's registration and health check. I had to set up my temperature every day on it.
Kanchanaburi, Chiang Mai, Bangkok, Ayutthaya, if you looking a total chill surrounded by hills Pai. Koh Chang. If you go down south Phuket, Krabi, Koh Samui, Koh Phangan .. lot of choices depends on your needs, budget, interest ;)