FYI - Delta requires one to get to the Istanbul airport three hours early. The IST web site only says 2 hours for international flights, but maybe Delta has had to do quite a bit of re-booking?
OP - did you try to do on-line check-in ahead of time? It hasn't been mentioned so far in this discussion. I've found more and more hotels are letting one get boarding passes right at the hotel.
I'll admit the Istanbul internet cafe scene is a little sketchy. Some pretty good, but some downright nervous-making.
Romelle