The best part of an afternoon may be the part nobody arranged to impress anybody.

Arranged moments carry an expectation, and expectation is a weight. The lunch that was booked, the outing planned for weeks, the occasion everyone dressed for: all of them are being watched by the people inside them to see whether they are going well. The unscheduled hour has nobody supervising it, so nothing has to succeed, and that is usually where the ease comes from. Enjoyment tends to prefer places where it is not being measured.

Leave a genuine gap in the weekend rather than filling every part of it. What happens in an afternoon with no plan is often the part you describe afterwards.