johnndor: happy travels! I just booked a OW ticket with AA for for this coming July/August. One key thing I learned - distance measured is between origin and destination, regardless of where you connect. So, one of my flights is Rome to Bangkok, connecting in Hong Kong. Hong Kong is actually further away, but the distance measured is only Rome to Bangkok as if it were nonstop. Use the mileage estimator that's on WebFlyer for help with this.
The other thing I learned is that only one "open jaw" is allowed. I had wanted to have four in my itinerary.
So, to net it out, plan carefully!
Silverpie: I don't think it's -always- blacked out, is it? For my upcoming trip, there were one or two days that the SYD-LAX segment was available, but the connection from CNS-SYD was oddly not. So, my routing instead is CNS-NRT-ORD (which is fine 'cause final destination is BOS, plus I have to overnight in NRT - 23 hours of sushi!).