Hi Doug -
South African Airways has a non-stop to JNB from JFK. If you do the 2 for 1 only one of you will get miles. The companion ticket doesn't qualify because the ticket is free. The price we paid was comparable to what we would have paid if we booked the ticket ourselves. Most of the time the 2 for 1 is not a good deal as the fare for one person is much higher than what you can find on your own. We rarely use it for shorter trips to Europe (i.e.Paris).
I don't blame you for not being happy about getting miles for Tahiti! Again, I got them but Al didn't! They are Delta miles though which I will probably never use.