Hi. In a quandary as how to book a couple flights. Would like to go DFW-JNB-DFW July 10th-26th. Will be purchasing business class on either AA or BA, with AA just a few more $s. Being an ExPlat with AA and Emerald on BA I'm trying to figure out which airline to purchase 2 tickets through that will make it the easiest to upgrade to first class. DFW-LHR it's the AA 777W and LHR-JNB the BA A380. I've plenty of AA miles, systemwide upgrades, and enough Avios. The Admirals Club angels at LHR have converted my BA ticket number on previous returns to an AA ticket so I could upgrade with miles and cash, but some of them aren't as willing to go through the steps to do this. Suggestions? Thank you!