One interesting type of vacation is the reading retreat, in which one travels away from home and daily routine, but instead of sightseeing or resting, one reads all day.
The routine on these vacations is very clear (read all day; don’t do other things), so they’re quite restful: Routines promote restfulness on vacation. You might be somewhere quite interesting, but you’ve pre-committed not to sightsee, so there’s no FOMO: FOMO on vacation disrupts restfulness. Significant language barriers with local people may amplify the sense of solitude and internally-located purpose (I haven’t tried this).
Reading retreats are solo (or effectively solo, given the expectation set of huge blocks of time spent for reading), which avoids coordination: Coordination inhibits restfulness on vacation.
You can avoid disruptions and distractions to your reading routine more effectively if you can conduct the retreat with no driving/transit. Resort environments work reasonably well.
For whatever reason, natural environments seem more effective than urban environments for these retreats.
I first learned about this type of vacation from Patrick Collison around 2015.
Conversation with Patrick Collison, 2019-12-27