The most important factor to middle class Americans in choosing where to live is the quality of schools because of their children.

Another difference in post-college living is that two-worker families are the norm and it's not always practical to live close to both jobs, even if the local schools aren't an important choice in home location: one of them probably going to wind up too far away from work for a bicycle.

I advocate fixing urban schools rather than exotic mass transit systems to best way to address commute problems. In many areas of the US suburban parents would consider moving into the urban school district a form of child endangerment. Making cities more attractive to live in would get more people to live near their jobs, and fixing the schools is the place to start. It doesn't solve everything (see two-worker families above) but it would make a big difference.