This year’s list is as follows (an asterisk marks places where I spent more than one non-consecutive night):
*Sofia, Bulgaria
Strasbourg, France
*London, UK
Istanbul, Turkey
*Tirana, Albania
*Skopje, Macedonia
Ohrid, Macedonia
*Oxford, UK
*Dublin, Ireland
Bratislava, Slovakia
Dubrovnik, Croatia
Berlin, Germany
Zagreb, Croatia
Lys, France
*Kidderminster, UK
Loughbrickland, UK
Riga, Latvia
Heathrow, UK (far enough out from London to count separately)
Helsinki, Finland
Belgrade, Serbia
Paris, France
Santa Rosa, CA, USA
Brussels, Belgium
That’s 23 cities in 15 countries, relatively high (though still less than 2016 or 2017). I also changed planes in Austria, the Czech Republic and Slovenia, and drove through the Netherlands and Luxembourg without an overnight stay, so the country total for the year is 20, again relatively high. Latvia was new to me.
World map:

Europe map, showing the family trek to Northern Ireland:

Central Belgium map, showing my two alternative commutes (up to Leuven and west, or down to Ottignies and northwest) and excursions with B around Tienen:

Leuven/Oud-Heverlee map, showing how little I venture beyond the shopping/restaurant streets in the city centre:
