I've always wanted to do the drive down the Mekong river from the top of Thailand down to Nong Kai and looking at the maps, it appears that once in the mountains, the road veers away from the river. Has anyone done this route ane can share experiences, route, places to stay, interesting side trips etc.....

Have 4wd truck, so can handle some rough roads.

I'm not sure if your map makes it clear but on mine The vast majority of the Mekong on the stretch you mention appears well within Laos territory so you probably wouldn't see much of the river there. I'm sure its interesting country all the same and I'll probably go that way sometime. I'll take the boat trip first though. The eastern stretch from around chiang khan near nong khai maybe a better bet for river views as it appears to follow the border right around to the border with Cambodia .