We have a variety of regional dialects here. In the city, I guess we sound like Californians (that's what people thought when I was in CA "are you from here? You have no accent,"). But we just watch too much TV, that's my theory, though I always wondered why we sounded 'just like those kids on the Brady Bunch'.
If you drive 100+ klicks south, the accent is thick, often hard to understand, with strong German influences (more what I would call a regional dialect, rather than an accent; ie, different words/terms.) . Go 100+ klicks in the other direction (my family home) and it's another different way of speaking.
Hop over the causeway to the island culture of my province, and you will 'stick out like a sore thumb' - everyone from The Hawk to Nart' Sydney will know you're a mainlander. Their speech is most colourful! : D
We don't say 'eh'; we end our sentences with 'right?' And i never heard the word 'hoser' before the McKenzie Bros. movie came out in theatres (Strange Brew). :P
There's French here (Acadian and just horrid to a Parisian - the dialect is hard to understand - France french is much easier - lol, probably because I studied it for 10 years)..
Aussies are the hardest to imitate. I'm somewhat of a mimic, and can do many 'accents', but not AU.
GB (the island) has so many accents & dialects! Even languages (thinking Welsh and Gaelic at least).. Would love to visit some day, and explore my Welsh & Cornish roots.
I can't recall anyone on Seinfeld that had what i'd think of as NYC accent, except for George's mother, Estelle Costanza "George! What are you doing, George!" in that screechy voice. hehehe
Oh, and we are the home of the Trailer Park Boys, which is a good representation of the local culture. hehehe