Thanks, number_6 for the very prompt response. I thought that I had responded several hours ago but my followup messsage seems to have disappeared somewhere in the depths of Patagonia. So here it goes again (sorry for the repeat if the earlier messsage eventually surfaces).

Thanks for ´reminding me about the BA MFU upgrade limitations, ret WT+.

As for the comparison of a DONE ex-NRT and a LONE ex-SCL with upgrades, here is what I was assuming. (1) Even though you can do a 3 continent from NRT I was assuming a DONE4 because I wanted to come back to So.am. again. Hence LONE4 vs DONE4. (2) Re the comparability: I was not taking into account the fact that you can use the VIP to upgrade a D ticket to A (so implicitly assuming no extra value for an A over a D) --dubious perhaps but a possible assumption, (3) If I can upgrade all the long haul flights then the only thing left as L are the intra-continentals. But for the No.Am. flights I should be able to get the "automatic" upgrades for EXPs-- or if not, say for the assurance on the transcontinental, use VIPs. And for the intra-Europe and intra-So.Am., most are short haul and some (e.g., about half of what I am considering) only have economy service anyway. So taking these factors into account is what I meant about LONE4 ex-SCL with upgrades being roughly comparable to a DONE4 ex-NRT-- and a lot cheaper! I hear what you are saying though, and will carefully examine each flight in the itinerary.

I welcome additional comments and challenges. Given the timing deadlines and my forthcoming inaccessibility in the further depths of Patagonia, I especially appreciate any other quick thoughts.