But if it's at all possible, plan your visit for the spring, autumn, or even the winter, when the big sightseeing destinations are far less crowded.
This destination is most crowded in the summer. 
mnli hypothesis: This destination is most crowded in the summer.  premise: But if it's at all possible, plan your visit for the spring, autumn, or even the winter, when the big sightseeing destinations are far less crowded.