If you are heading Mali from Mauritania and want to avoid Senegalise border (Rosso/Diama), most straight forward, less expensive option is to drive through Nouakchott - Aleg - Kiffa - Ayoun - Nioro - Diema.
Now all route is asphalt, only some potholes between Kiffa- Ayoun but if you go slow, there's no problem.
Border crossing at Gogui(Mauri/Mali) is very peaceful. 3000UM for customs
on Mauri side, and 5000CFA (Sat&Sun 10000CFA) for customs in Mali side.
(Police stamp additional 3000CFA)
Carte Brune for ECOWAS is available at the Malian border for the price of
1month: 24657CFA, 3months: 28388CFA, 6months: 47045CFA,
this insurance covering most West African countries inclulding Ghana.
Places to stay on this route (2010):
Nouakchott
"Auberge Sahara"
GPS: N18°06.163 W015°59.854
1800UM per person. Hot shower, Kitchen, Free WiFi!
#Walking distance to Malian Embassy.
Aleg
"Auberge L'espoir"
GPS: N17°02.939 W013°54.923
Need to negotiate, putting tent on the terrace was
4000UM for 2 people. (Air conditioned rooms 8000UM)
Kiffa
"Camping Le Phare du Desert"
GPS: N16°38.758 W011°26.854
Camping 2000UM per person. Nice restaurant covered with plants.
Ayoun
"Hotel Nezaha"
GPS: N16°39.810 W009°35.859
Camping at the terrace 2000UM per person.
(Rooms 15000UM! Maybe the best hotel in town?)
Diema (Mali)
"Village Ventures"
Village Ventures Home Page
GPS: N14°33.036 W9°11.184
This is a development project run by an English lady.
Walking dictance from the roundabout. Near water tower.
Camping about 5Euro donation per person.
Hope this information helps.