Either Ground Zero, or Bolivia.
Hell, you don’t even have to leave the US for that, just come to Cincinnati.
In case of major nuclear action, ground zero with my family, could not stand watching them go through long term illness and pain caused by fallout.
Minor nuclear scuffle with nukes on the coast, and maybe DC and New York? I’ll take my chances staying put, although I probably will invest in some firearms. Only issue with this is the jet engine plant to the south, and the “retired” AFB to the north.
If it’s the US and N. Korea fighting it out, I’d try to be on a boat headed for Ireland. I’d pack up the Celtling and our emergency bags and head NW 'til I got past the mountains, then to the Philly or Boston seaports to try and get passage. Any boat headed to sea will do for a start.
If I thought the European continent was going to get involved then I’d try to get to South America. I’m looking for anyplace with plenty of fresh water and where it doesn’t get too cold in Winter. That’s 80% of survival taken care of right there.
In Austrailia in a 1973 XB GT Ford Falcon Coupe.