Thanks for the great responses!

As far as picking a FF program, I do a lower-tier elite level of domestic US travel centering around the East Coast (and a lot of ATL-IAD trips). I like using miles on FF tickets and hope to go to Asia next winter. I'll have to look at AA's schedules for routes I frequently fly.

So far as the 'no AA credit on BA' flights, do you have a pointer to where I can look to dig up the rules on this? Why would I get credit then for traveling LHR-YYZ after July 1st? (And my trip would be all of August and into September.)

I'll definitely look into the SYD-JNB flight. For some reason I thought it was an ineligible codeshare. I don't need to go to Asia, I just thought I had to for routing. This'll cut down to a OWE4 which would be good, and let me disperse more time in Africa and Europe.

I also looked into flying MUC-LGW-ATL on the final stretch, all in one day. TXL just seems like a tricky airport for connections I'd want to make. I think I'd have to be mad, however, to do something like TXL-LHR-YYZ-ORD-ATL in one go. I had a bad time last year with BUD-CDG-AMS-JFK-IAD (I think it was).