Good of you to post this, OP. But anyone who isn't familiar with the BA program should be aware that it charges very high fees for award redemptions that involve flying to or especially connecting through LHR. My wife and I used this deal, including the companion ticket to fly SFO-LHR-DXB a few years ago, with a stopover in LHR. IIRC, cost us over well over $3,000 plus the points. Of course, you can view that as using the miles for a de facto economy ticket, but it nevertheless adds up to the BA awards costing more than almost any other program.

Redemption cost$ for partner airlines not going through LHR are not as bad, with using Avios to Latin American being very low. But of course you only way you can used the companion ticket is on BA, which means you'll pay through the nose to avail of the companion ticket option.