A word about upgrades...
I was on a mileage run this past November (Nov 2013) with BA segments of LAX-LHR and LHR-JNB (and returns). I used BA flight numbers and was on BA ticket stock. Unfortunately to save a couple of hundred dollars I booked using Orbitz. BA seems to have a rule that only BA ticket stock purchased directly from BA qualifies for any type of upgrades. Only on the day of flight can you check at the airport to see if any upgrades are available.

In my case I only found an upgrade (at the T5 lounge) from LHR to LAX going from world traveler to world traveler plus for around 200 pounds.