Thanks to those above for your assistance. To let you know how it played out- we missed our connection to Rome and went to the Turkish lounge and re-booked for the next morning. Our checked bags will hopefully be on that flight with us. (we never check bags but were forced to at the Altanta gate because of the weight of our main bags, which was unfortunate). Rather than deal with the airline's hotel, I used a Hyatt FNC to book the Grand Hyatt which was great. I am here now. Then we cabbed to the Blue Mosque area last night. So it ended up being fine with an unplanned stop at very interesting Istanbul.

My one criticism of Turkish is that their FLight 32 from Atl-IST does not adequately allow for the standard delays for onward connections of 1.5 hours like FCO. The Venice connections on our flight also missed it. I would not rely on FLight 32 again for a connecting route. The flight history shows many delays.