Actually, Mekong Hotel is in Thakhek, not in Savannakhet! It is the one, which is also recommended by lonely planet. That's the reason why we booked a room at this hotel.
However, our night at the Mekong Hotel was absolutely horrible!!! We knew that we would reach Thakhek after midnight and therefore booked a room via agoda.com at Mekong hotel because it offers a late check-in option. I also mentioned our late check-in as a special request and even called the hotel on the same day. They assured me that it was no problem. However, when we reached the hotel at night there was no room available. When I showed the receptionist the confirmation of my reservation, she didn't even check on the computer or reservation book if there is a room. She didn't speak English and just went back to sleep into her room! Our friend was looking for another room nearby but soon came back saying there was no room for us. As the area didn't look safe we decided to stay at the hotel and sleep somewhere on the floor. There was no roof, it was freezing cold, dirty, noisy and we even heard rats running around. So we didn't sleep for one minute and left the place at 5:30 am in order to catch the first bus out of the city. Mekong hotel is a place you cannot trust and where people don't care about you if they cannot make money with you. This had never happened to us before in such an aweful kind of way and was the most horrible night we had during our whole trip!