What to do at IST Ataturk airport late at night?
 

I have a very early morning flight at IST to HAN. It's at 02:25. I do have a Priority Pass .just wondering what I should do or if there is anything to do at the airport? I didn't book a hotel for that day as I saw no point. I'm probably heading to IST from Sultanhmet at about 10:30 PM or even 11 PM. Last train is at midnight right?

If I remember correctly, the last train may be before midnight - check the site.

PPass gets you into one of the lounges, which is pretty solid, though not as good as the TK one. A flight that leaves at 02:25 will mean boarding as early as 01:25, so you'll only have an hour or two to kill.

Why do I have to board an hour early? TK lounge isn't available to PP users? Which lounge should I go to?

If it's a bus gate, you'll need to board that early. Usually the actual boarding starts at T-45. Check the PP website for what's available, but the TK lounge is not one of the choices.