I too am currently growing up in a northern (nawthin) suburb of Boston and yes, this conversation has come up many a time between me and my peers. In my town, a Boston accent is rare among the younger generation, but, like wukong888 said, common among their parents. My mom, for example, grew up in Somerville, and regularly talks about tawnic (tonic) and taking bahths (baths. Pronounced almost London-like).
However, I would like to clarify some things:
Number one: If you went to Harvard Yard (yeah yeah pahk'd yeh cah theiyah), you could very easily order a soda and receive a Coke or Mountain Dew or the like. We're not so insular to consider drinks of that ilk to only be "tonic". I call them sodas myself.
Number Two: On The Usage of "Wicked": Using "wicked" as a synonym for good is a skill, an art, if you will. We don't say wicked good that often. The word is best used in passing, said casually. If you come flying out like gangbusters with something like, "HEY GUYS! WICKED NEAT GAME THERE HUH?" you will most likely be looked at oddly. Same goes for looking at something interesting and proclaiming "Wicked!". No one does that. Wicked is meant to be used as an adjective, not an exclamation. The most common use of it (nowadays, anyway), that I have noticed is "wicked sweet", i.e. "Yeah I know, it was wicked sweet". There's a certain level of apathy and subtlety that it needs to be said with. Well, we've got that cleared now.
Plus, there are several regional accents: Boston (Bawstin), Somerville (Summihvil), Revere (Reviyah), Medford (Medfid), Billerica (B'ricca), Worcester (Woohstah), and Chelmsford (Chemsfid) all have discernible differences.