Could add Muang Tam, Phanom Rung, Si Satchanalai and a few others.
But, to be honest, I often wonder why so many tourists come to Thailand, where there isn't much of genuine interest to be seen. While in Europe or even Latin America every village, every corner, is an attraction, often surrounded by amazing scenery.
Can't believe it is the seedy reputation of the country that can draw so many.