If you live somewhere that's reasonably dense, this is possible. I live in a very walkable city that is also socially quite dense. Most of my social links are people who live a walk or a short bike ride away. During the warm months, if you are around town you will see people you know, and have the option of conversation.
Put simply, you feel like you live in a community without having built a commune or something.
Unfortunately it's kind of hard to tell what cities have this "social spatial density." There are denser urban areas that feel less communal, and far sparser ones that seem moreso, it's related to overall population density but not perfectly so.
Rather than what city, I'd say you need to find out what neighbourhoods in each city. I used to take a 1h commute to a community garden for the people there, instead of helping at the utilitarian community garden on my own block. Moving there would have been great but it wasn't affordable. Didn't prevent being treated like one of the neighbours each saturday!
Put simply, you feel like you live in a community without having built a commune or something.
Unfortunately it's kind of hard to tell what cities have this "social spatial density." There are denser urban areas that feel less communal, and far sparser ones that seem moreso, it's related to overall population density but not perfectly so.