I believe Air Tanzania is a partner of sorts with South African. In the current *A configuration, South African would be convenient for the trips to southern Africa you mentioned, but in the discussions of which *A FFP to join, SA never comes up as one of the top 3.
I suggest checking the charts in the stickies at the top of this forum, plus a couple of long threads discussing the pros and cons of the various FFPs. It seems like you should get *G on just about any airline with your travels, so lounge access is given, but beyond that it goes down to personal priorities.
All the best for the big move!
Last edited by cloudcuckooland; May 15, 2009 at 12:51 pm