In January 2010 I stayed for a few nights at the relatively new Ban Mae Rim Nam, situation right on the riverside promenade in Nong Khai. The hotel has lovely, light-filled riverfront rooms for 700 baht per night, which include everything you'd expect from a 3-star hotel, such as spotless hot water baths, cable TV, fridge, free in-room coffee, etc. But the real value is the unparalleled river views and people watching through floor-to-ceiling sliding glass windows or from the small balcony on each riverfront room. Ban Mae Rim Nam also has non-riverview rooms for 500 baht, but without the view they aren't worth the money.
The Ban Mae Rim Nam is located about one-third of the way south on the riverside promenade, directly towards the river from the post office, and has a variety of Thai and western food restaurants, bars, and internet cafes within a one block radius.
For more information, check out the website listing at http://baanmaerimnam.nongkhaiinformation.com/ or call 66(0)42 420256.
Even though the staff seemed chronically confused, staying here was exceptionally relaxing and a great flashpacker splashout for a few nights.