Originally Posted by aztimm

Sorry I forgot to follow up on this.

The reason I flew AUS-JFK-GIG was that there was a fare deal that required me to be on the JFK-GIG flight. On the return I flew GIG-MIA-DFW-AUS. At least when I made the trip, there weren't any nonstop flights between DFW and GIG. I think there are only 2 MIA-AUS nonstop flights daily, and neither worked well for me.

I checked in for my whole trip in Austin (AUS-JFK-GIG); checked a bag all the way through, and received both boarding passes. My AUS-JFK got in early, so I had over 8 hours. I stopped in the club (I had heard a rumor that they may let me leave my bags there, but not true) briefly, then headed down to baggage claim. I left my bag at the left luggage desk, then took an Uber to Brighton Beach, met a friend to swim. The water was freezing (I asked her not to tell me until we finished, she then told me it was 61F). After that, I walked down to Coney Island, ate at Nathan's (the main one on Surf, across from the subway station), then took an Uber back to JFK.

I'd guess I was back at JFK around 7pm. Had plenty of time to retrieve my bag, clear security (TSA Pre), visit the lounge (with a shower), have some snacks and relax, then head to my gate.
As someone else mentioned, things were pretty quiet in T8 by that time and most people in the lounge were on my flight to Rio.