What I got is SFO-CDG actually. Maybe the reverse can work. CDG-ICN-SGN-NRT-SFO . Will try to price it. That would be one more city.

I think most likely I will go with the CDG-SGN-PVG-SFO plan, though, as outlined above, as it less cash outlay .

Also, my husband won't be flying the initial part of the trip. While I go to Paris to visit family, he will be in Saigon alone.
He will fly for $572 with China eastern . Unlike me, he can tolerate a 25 journey. So, he will fly SFO-PVG-SGN-PVG-SFO . And I will meet him in SGN and then spend more time in Saigon together, then visit Shanghai together, and finally get back home. We'll be on the same last 2 flights , but different bookings.

I found yet another hidden city ticket :
SGN-PVG (China eastern), PVG-SFO (China eastern), SFO-LAX (Delta) .

First two flights on one booking are $738 . All three are $758. Ie. the last flight only adds $18, so it doesn't save money. But by booking it on Xmas eve which is still available, I'm thinking I can arrive last at checkin, volunteer to get bumped, and get more than $18 worth of cash compensation to get a nice Xmas dinner in a restaurant in SF. I would never board on the SFO-LAX flight no matter what, though. Worst case I lose $18 and a bit of time at the airport if it's not overbooked. Someone tell me why this isn't a good plan