West Africa is the western region of Africa. In the north the region is bounded by the Sahel, and in the south and west by the Atlantic Ocean. The most densely populated area of Africa with many places to see.
The African highways connect many cities in West Africa with Nigeria being the main hub.
Flying from other African cities can be dangerous as many airlines have a very poor safety record. Check this first before choosing to fly with an airline.
In order of size here are the main airline hubs.
Generally it takes time - and a whole lot of patience - to move around in West Africa. The roads are not all in great conditions and many roads aren't paved. Always be sure to have an extra day or two in the end if you are going somewhere since planning is very hard when the transport is unreliable.
Go to Benin if you´re interested in voodoo because this is where it originates. There should be plenty of opportunities to go to voodoo festivals and fetish markets.
Mali has Dogon-country which is a world heritage site. Also go to Timbuktu/tombouctou - the city known from Donald Duck magazines - and Gao which contains yet another world heritage site.
If you're interested in meeting some of the world friendliest people go to Burkina Faso or Ghana.
Don't drink tap water unless you have a cholera vaccination which also protects you against tourist diarrehea.
Make sure your water bottles are sealed and not just refilled with tap water. It can be hard to see.
West Africa is probably the one place on earth where you should protect yourself in every way from mosquitoes. Do not sleep without a net and do not go without malaria-medicine.
Also you need a yellow-fever vaccination to enter most (if not all) of these countries.
Remember to check all of your other vaccinations because many other might be necessary (meningitis, typhus, cholera, rabies).