A good question.
A local answer.

Check the exact peninsula destination; reaching a town does not leave the same time as visiting a distant attraction.

For an awkward outer attraction, compare one direct transfer with the full cost and effort of hiring a car.

If an iconic distant stop creates hours of backtracking, add one overnight or leave it for another trip.

Compare a central base with one near the relatives by the actual door-to-door journeys, not suburb names alone.

If a journey crosses the boundary, use the correct fare method from the required point.

Map the two areas on opposite sides of Melbourne and choose a sequence that avoids crossing the city repeatedly.

Keep one indoor stop in the itinerary so a weather change does not waste a whole day.

Check current weather, trail access and cancellation terms close to departure; winter conditions vary by day.

Map late transport from Melbourne Park to shortlisted areas before comparing weekly prices.

Group each day's food and transport around one main area so changing plans remains easy.

Use the same valid fare method throughout a journey and check concessions separately.

Allow daylight for coastal roads and rest between walks.