Nong Khai has good Vietnamese food. Udon has good farang food. Khon Kaen has good Japanese food.
Udon has the best choice of hotels.
25 baht to travel between Udon and Khon Kaen via train.
I don't know why he keeps going there. Always unhappy.
I went to Bangkok, Korat, Khon Kaen, Udon, Nong Khai, Bueng Kan, Nakhon Phanom, That Phanom. Had a great time.