Best bet for what you decribe is is Flybing Blue (Skyteam), but that is only nice if you are flying WBC or full economy. KL has 1 daily flight from Dar to AMS and via NBO (which is easy from DAR) you can fly twice to AMS daily.

Your hub for Africa will be probably be NBO with Kenya Airways. Emirates flys to DXD daily so that could also be a possibility.

(I work in Arusha but do not live in TZ (2weeks TZ 2weeks AMS is my schedule)

(if you are working for American Company or Government you will have to fly KLM)