hmmm. kinda reminds me of lawrenceville which is only 30 blocks from downtown.
as a foreigner (from NM and the southwest) who has spent about 6 summers there, i can say i felt what you describe, both as a kid and as an adult.
im not too familiar with suburban pittsburgh. but ive taken hunnerds of bus rides, to go to the games, downtown, the malls, kennywood, to the museum, etc. so that tells you the majority and the types of folks ive encountered. lots of interesting characters on the bus.
its a very culturally diverse bunch and a bit more segregated (as i suppose most big cities with large immigration populations are) compared to what im used to, growing up on military bases and in indian/mexico country.
ive been looked at funny plenty of times walking by a stranger sitting on their porch and saying "how ya doin?".
of course in a southwestern small town a smile and a nod, or a tip of the cap is just a common courtesey and making eye contact isnt considered a threat.
but i LOVE it. i love the old row houses, all the different people, the brick streets, the city smell, living a block away from the allegheny, taking a walk across the bridge or up to the cemetary. strolling the strip or hanging out at market square just to people watch. i love how every neighborhood has a bar...or 12! (down here there are zoning issues). i love going to Gators for a liquid heroin and a puerto rican monkey f*(k, and to frankies for a polish sausage and a carry out beer. i love just sitting and listenning to all the regulars and then getting in on the conversation.