Nouakchott is the largest city in and capital of Mauritania.
The Novotel and Hotel Mercure set the standard for nice places to stay, but you will pay European prices. The Hotel Halima, just behind the Novatel, is slightly less expensive. In central Nouakchott, the Hotel Houda and Atlas are not bad options. There are also a couple of "camping" places not far away.
There is also a hotel out at the beach with "hut" rooms and a big dining room overlooking the water.