Highly recommend Warrnambool as far as regional Victorian towns go, but the lack of humidity, constant wind and freezing water would take getting used to after Thailand. The Sunshine Coast or Cairns have a similar vibe but warmer weather.
Definitely will not miss the humidity/heat. I'll miss the weather being fairly constant though.
Also, no to Qld. We want to move back to Australia, not move back to the 1920s.
Portland is nice, but Port Fairy is possibly the best little town along the West coast. I grew up in Warrnambool, but spent a few months house sitting an old whalers cottage there.
I get your point about Queensland. Maroochydore might be slowly modernising. They're building a new city centre from scratch on what used to be the golf course. They've recently connected to the Japan-Guam-Australia South submarine fibre cable and the council are marketing that pretty hard. Saying that, it's still largely seen as a place to retire; evidenced by one of the largest contributors to the local economy being healthcare (which includes nursing homes).
The old growth forest parts are amazing and you used to be able to camp some places in there and even take along the dog. I live within walking distance of a comparable waterfall but can't take the dog due to its park classification.