Try to get on a flight to SFO?
Otherwise I would say do the ATL SC crawl. Showers in F are nice and I could spend hours on the SkyDeck (though not as nice as JFK which has a greater variety of plane types / airlines) -- B is nice when it's empty (my last 3 times have been between 10-11pm before the late ATL - RDU and it's been completely empty and nice).
I find The Club across from F to be highly overrated but if you have time I guess you could check it out.
Despite what the FT thread would have you believe, my last few OFS experiences have been just as good as in the "old times" so would stop by there for lunch as a break from the SC (and it's around the corner from E if you want to check that one out).
I believe there is a Minute Suites in B that you can get into with Priority Pass but have never gone (wait times have been too long) -- but given your early arrival and likely interest in sleeping, might be worth heading there first and trying to grab a bed for a couple of hours before you start your pub (I mean lounge) crawl. Believe Minute Suites pricing is first hour free and then $28/hour after so a quick 2 hour nap for $28 isn't a terrible value prop.