Originally Posted by leoo

I'd suggest Brazil, it's possibly the furthest place you can travel with UA (Dubai or Turkey if UA is not a requirement).
Brazil is open for tourists and the only requirement is medical insurance coverage for the duration of your stay.

You can do EWR-GRU arriving at 6:50am and departing the next day at 9pm, not sure if you'd even need health insurance in this case.
And the Star Alliance lounge in GRU is open 3pm-11pm.

I understand the need of getting on a plane again and will be spending some time in Brazil.