Hey! I'm from South Australia, and i recently moved to Queensland last year. I think accents all depend on where you come from and your family history. I've read here some people think SA's speak with an almost English accent - well, coming from there i would agree but it differs from person to person. My mother is English so i've been asked many times by several people in SA if i come from England. Generally speaking, people's O's and R's are more rounded and pronounced in SA. If you come from the York Peninsula, people there generally pronounce their L's as W's or Y's, such as Miw-yen for Million.
I've found that people who come from Victoria or, and particularily, NSW pronounce tool, school as toooool and skoooool. And also graph (instead of graRph as its pronounced in SA) they pronounce it like graph as in graph-ic. This is how my friend from the Victorian/NSW border spoke. Also branch and plant (and all words that rhyme with them) were pronounced brahnch and plahnt (instead of br-ar-nch or pl-ar-nt in SA).
In Queensland i've found its similar to Victoria and NSW, except they don't pronounce tool and school the same way. They pronounce project as proh-ject, very similar to the way American's say it.
I haven't been to Tasmania, WA or Northern Territory so i can't make any judgements. I do know that the more 'outback' you go the more broader the Australian accent gets, or you get the Crocodile Dundee type accent there. The slang is also used a lot more often and is hard even for some other Australian's to understand.
I don't think it matters much really. And to a previous comment, no SA's don't think they are still a part of England and we are in no way snobby people. Its just an accent. So, from my experience i'd have to say i agree with you that from state to state there is a variation between accents. Sometimes only slight, sometimes very noticeable.