My anecdotal two-cents on medium density housing

My friend Chris lives in Philadelphia in one of the medium-density neighborhoods Atrios refers to. He is happily carless, walks to work and takes the train when visiting friends in other cities. When I went to visit him, we ate at a Cuban restaurant just across the street and then went sightseeing on foot the next day. He likes Philly because it's small enough to be manageable and not too alienating but large enough to have interesting restaurants and businesses. And rent is not nearly as hellish as some of the bigger cities.

Any other smaller cities in the US where this kind of lifestyle is possible?