Bro, the road to Nong Khai you took is Motorway No. 2. This is the main road that passed by the big 3, Korat, Khon Kaen and Udon, and connect to two third of Issan. Dont worry, have never heard anyone getting lost on motorway no. 2 cos its straight all the way from start at Saraburi to the end at Nong Khai. The only possibility of getting lost is after exiting from motorway 2 and entering the rural roads. This I admit lost many times. The other road that connect to the remainjng one third of Issan is road 22, 23 and 24. These roads are much much more tricky as its not like motorway 2 that goes straight. I am more confident of using motorway 2 than the Ubon bound roads 22-24. Lots of confusing road signs(hard to survive if cannot read Thai) and lots of border matas and soldiers road blocks.