I've also been planning my route for the last couple days and just booked my first leg covering Africa & Australia with ICN-IST-CAI-IST-SYD for $1400 in Y.
Because of my schedule I'll have to cover SA last in early October. I'll be starting at LAX, and my initial thoughts were to book LAX-IST-GRU Y on TK for $1170 but found LAX-IST-ATH-IST-GRU flights around the same time for $870. Are there any other destinations that might have lower fares from LAX or to GRU/BOG that I should consider? I've checked BUD/TLL/RIX but these seem to be more expensive than ATH.
Another option would be to fly from LAX to a city in Europe with another carrier (seeing one-way direct flights to FCO, BCN, CDG for $200~$300) and fly to GRU/BOG through IST with TK - the only problem is it seems as though fares from those airports (FCO, BCN, CDG) on TK to SA are pretty steep.
Would welcome any input!