I tried once more - today in fact - with the 800 #. I'm hard of hearing and had an extremely difficult time understanding the woman's accent. I gathered something about having to wait until October for seat assignment. My flight is mid January, so I assumed some kind of 90 day rule.

That, or there's an aircraft change. The ANA tool shows the IST-ORD-IST route switching from A343 to A330 on October 24. Thus, my January flight shows A330 with ANA. However, TK website still says A343 for the route regardless of date.