Doing EWR-IST-BJV in a couple months but after reading through this thread, I realize that we don't get international biz lounge access since we'll be transferring to the domestic gates for the 2nd leg. Even though we've transited through IST a couple times already during Fall 2021 (for international departure or IST being final destination on arrival), we've still never gotten a chance to access the biz lounge since it was closed during that time due to Covid.
Domestic lounge offerings don't seem that great, and due to a schedule change, we actually have a 4+ hour layover rather than the previous 2.5 hr layover. There is still an option to change to an earlier IST-BJV flight that would only be a 1h20m layover, but that seems a bit tight even with the expedited business security lines