A good question.
A local answer.

Compare start times with dinner and the journey home; a cheap second ticket is no bargain if you cannot reach it.

Reserve the small coastal towns you most want for summer dates, then leave daytime detours flexible.

Join a hotel programme only if its actual rate or useful benefit beats the public offer for your dates.

Look up the current parade route and Adelaide Metro detours; an ordinary airport bus plan may not work on the day.

Allow for traffic and a missed connection; arriving at the terminal early is worth more than squeezing in another stop.

Ask the hotel to hold luggage first; dragging cases through a market and altered event routes costs more time than it saves.

Compare an airport taxi rank vehicle with prebooked rideshare or a larger transfer, including pickup fees.

Glenelg sounds like the likely match: compare old memories with photos of Jetty Road and the foreshore before committing.

Confirm cot, parking and late check-in needs with accommodation, and keep the final Melbourne nights free of long drives.

Hold a cancellable room while you compare dates; do not assume a distant bargain will save money after transport.

Pack layers for both city and inland travel, and check the forecast for each destination rather than assuming one winter pattern.

Treat the food as one part of the day and include a short walk or nearby stop so one pastry does not carry the whole trip.