A good question.
A local answer.

Plan a route with safe crossings and enough daylight, accounting for luggage.

Choose a location and time that does not block paths and has a weather fallback.

Compare the live tour itinerary and time inside the tower, not just the keepsake.

Pair the ride with a walk or meal at the destination and check the last return service.

Check the grade and transport for any Bibbulmun Track section before treating it as a quick city walk.

Walk together, keep ordinary city awareness and use a short car ride if the route or weather feels uncomfortable.

Pick one neighbourhood or waterfront walk for the arrival day, then add a larger outing once you know your energy.

Add one riverside walk or lookout and one lunch stop, then leave the rest flexible.

Give each weekday a different pace: central sights, a Fremantle day, a coastal outing and one flexible museum or garden day.

Map the last leg from the stop to your hotel before dinner, especially on a quieter weekend street.

Treat any light show as a separate current-schedule check rather than relying on an old forum report.

For wildlife and an island feel, allow a full day or overnight for Rottnest and arrange transport ahead.