Another datapoint-- I had luck booking a TY companion ticket on AA JFK-SFO.

The lowest fare from AA booked into O class and was $317 all in. $317 was also the lowest fare offered from UA, DL, VX and B6 on my travel dates, and I was offered options from each airline through the Spirit online booking engine. Unfortunately, only 2 AA options were offered for each of the outbound and the return, even though when I checked with AA, every flight on each travel day was the same price.

My total for the two tickets through Spirit was $414, so a savings of $220, so I definitely feel like I received sufficient value from this benefit for this year, even if I had paid the annual fee (I just got the card, so the fee is waived for the first year).

I was able to enter the AAdvantage numbers for each flyer on the Spirit website, the itinerary immediately showed up as linked to my account on AA.com (and the e-ticket receipt through AA shows that the tickets were booked into O class), and I was able to request upgrades using my 500-mi stickers.