What is the primary feature of an excursion in travel?

The primary feature of an excursion in travel is indeed a sightseeing event outside the city limits. Excursions are typically designed to provide travelers with opportunities to explore areas of interest that are located away from their main accommodation. This can include visits to natural landmarks, historical sites, cultural experiences, and attractions that are not within the urban center where travelers are staying.

Excursions often involve organized tours or transportation, allowing participants to experience new environments, learn about local culture, and engage in activities that are distinct from their main travel itinerary. This contrasts with the other options, which do not capture the essence of an excursion. For example, a trip with no guided services does not necessarily constitute an excursion, as excursions can be guided or non-guided. Similarly, a journey longer than a week or a vacation package to a resort do not accurately represent the focused, off-site nature of an excursion.