I found with Adelaide that everything was very close wherever you were and if you lived towards the hills, you'd only be 25/30 mins from the beach and on the coast, only 30 mins to the hills. There seemed to be good access from most suburbs to the CBD, although I noted that some of the suburbs that were nice along the coast, for me were too far if I had to go into the CBD each day. While it did feel small, to me, it had everything I would need and if I wanted the big city for a weekend, it was only two hours by plane. As with Perth a lot of the suburbs sprawled into each other, but that's no different from driving into London or Manchester. I did find some lovely beaches towards the south which looked nicer than the ones in Perth, or certainly more picturesque. Brisbane I liked more for the access to The Sunshine Coast and Gold Coast and while the city was much like any other city, it just felt there was more of a buzz about the place than Adelaide and Perth. Yes, you're right, the beaches aren't on the doorstep but for me as long as they are within a 30/35 min drive that's all I want because I'm not a beach-bum and only want to go there for walks or a relaxing day in the sun.
I often judge places by the amount of photos I've taken and in Perth I struggled to take that many, which to me shows it's missing something as I'm usually snap happy. I'm sure most people that live in Perth are very happy, but I don't want to live in a Benidorm where people just go there to be just like home and miss out on the bigger picture of embracing life in a new culture.
This is just one persons view, and I maybe more particular about where I live, but I left feeling so disappointed as I thought it would be the place for me. But now I know it's SA or possibly Queensland where I will focus on my next trip.