Thanks all for your input ^
I'll have a play around with ANA to see what might be available. I knew about the TAP option and was considering between the shorter travel time this offers versus avoiding TAP because I've read few bad remarks about them. That said, the UA flights are, I'm guessing from other threads, not likely to be using the spanking new config for first and business (both 763s).
I wonder if anyone has any thoughts of how TAP in C would compare with UA C and then UA F? Would I also be right in thinking that there could be a possibility of a downgrade should the reconfigured aircraft be in operation, given the lower number of seats, especially with a reward booking?
Finally, if I did continue with the itinerary as planned what lounges might I be able to use? Having checked out some websites, it looks like there’s a Varig lounge in GIG – would I be able to use this or would it be something else? Also, I note that there is a technical stop in GRU for a couple of hours – is there a lounge I can use there? Thanks!