Bringing my own thread back from the dead...

Many, many thanks for all the replies. This was very helpful. I just completed the following journey:

EWR-ATL DL847
ATL-EZE DL101
EZE-CDG AF415
CDG-SIN AF256
SIN-BOM SQ422
BOM-JFK DL17
$13K total, all-in (all J fares, except Y on first/shortest leg)

All ST, except the SQ hop (and with CO joining *A, the miles will be useful, eventually).

I enjoyed my 12 hours in Paris.

Some random thoughts on the various flights:

- On DL101, requested only main course, and that it should be delivered as soon as possible (I wanted to sleep). It came at the same time as everyone else's. Not the first time this has happened on Delta. With CO, this request doesn't seem to be a problem.
- First time on AF. Business class was fine. Slept and ate well, although the wine was mediocre. Also, the pilot frequently switched the seatbelt light on/off and, each time, an FA would make a bilingual announcement. I am used to only emergency PA announcements on overnight flights.
- First time on SQ and service was outstanding (not surprised). Awesome hot towels.
- BOM-JFK on DL was excellent. Lie-flat seats were a blessing (10+ hours sleep in total). Food was decent. Flight crew seemed upset to be there, for some reason (stark contrast with SQ). However, I am not a needy passenger, so it wasn't a big deal for me.