The best and nicest way to get to Timbuktu is by riverboat. It does take a long time to get there by this route. From Mopti it takes about three days with stops at villages along the way. If you want more than 2 or 3 stops, arrange to spend 4 days on the boat. It costs 300,000CFAish to charter a pinasse - technically it'll seat 20, but more than 6 people will be cramped. From Gao takes 3 to 4 days. You will see good bird life as well as the life of the local people, and particularly on the Gao route should be able to see hippos. You can fly to Timbuktu from Mopti or Bamako a couple of days a week.