The site at Sukhothai is a stylish park, where you can explore the ruins by cycling from one monument to the other. The statues and temples are much better preserved (though several centuries older!) than the ones at Ayuthaya, or is that just my imagination?

Sukhothai is more than 400 kilometers distance from Bangkok. I stayed at nearby city Phitsanulok, and went to Sukhothai by local bus, a good option.