On my way down to the Gulf of Thailand to do some scuba diving, I stopped off at Sukhothai to see the 13th-century ruins of the Sukhothai kingdom. Somewhat similar to Angkor Wat, but much smaller, the ruins are easily accessible by bicycle and entrance costs just a few dollars. Sunrise at the temples was particularly striking and worth waking up early for.
In addition to the temples, I had a lovely time staying at Sila Resort, a nice hostel in New Sukhothai. I’d highly recommend it!