I don't know where you are or where you're from, but this reads to me like you'd really enjoy New York City. Not everyone likes big cities, of course, and not all big cities will match my explanation. But bare with me for a moment.
I spent the majority of my twenties and some of my thirties in NYC, and it does match up very well with what you're saying. It definitely matches the habits I was alluding to as well.
I've spent many a night on different roof-tops around the city. Most people have tiny apartments, so we tended not to visit one another, except for the occasional golden jewel of apartment - rooftop access. During the summer, there's almost always someone throwing a rooftop party, and we visited often (or had our own).
Likewise, the parks are everywhere. They're immense, amazing, well-maintained, and well-visited by people from all walks. I've spent day-after-day in Union Square, Prospect Park, Central Park, whatever that park is along the entire West-Side-Highway, and Battery Park (amazing sunsets). Sometimes just to people-watch and sometimes to meet up with friends as we figure out our next adventure, but always an inviting place to be.
There was also a trend in NYC - as I was leaving a few years ago - to start replacing major streets with pedestrian parks [1] (including Broadway in times square!), which I was 100% all for. Most locals I've known have been huge fans of getting cars out of Manhattan and making the streets more pedestrian-friendly, whether it be through tolls or just plain closing off major thoroughfares.
And honestly, after living in 4 major cities around the US, there is nothing like going for a long walk around NYC. I'm in Chicago now, and walking more than 1.5 miles can get a bit tedious. I still do it in the warmer months, but it's still very much a driving city. In NYC, 1.5 miles is always interesting. You'll pass through three or more distinct and lively neighborhoods along the way. There are so many people out, so many buskers and people enjoying cafes and parks, that you _want_ to walk everywhere. There are plenty a night, while I was single and dieting, that I'd walk all the way home after a night out - through Lower Manhattan, over the Williamsburg bridge, and about another mile to Bushwick. Loved it every time.
At any rate, my post wasn't in disagreement. It was merely an anecdotal description of _why_ we end up in commercial establishments in our younger adult lives. Overall I agree with you, and what I'm explaining above is that I've seen some form of what you seem to see as an ideal in action, and I'm an enormous fan of it.
1: http://www.pps.org/reference/broadway-boulevard-transforming...