This is very helpful, thanks everyone. I actually do want to stop in YUL on the way out and the way back, so it's a 4 segment trip for sure (which I need to book by calling the agents). And my ultimate destination is in fact IST, but that's a very interesting notion re: being inside or outside of Europe 1/2 zones, I'm going to look at that a little harder. It's easy to get to IST from inside Europe anywhere...

I've heard that Business in Air Canada metal is a lot better than Biz in TK metal - is that true? I do want to travel Biz on all segments...

THANKS!