1: which is, really, not THAT much more in terms of cost per mile than using public transportation
And that's entirely a function of bad city design. When I lived in New York, I lived in a Westchester suburb satellite city over 20 miles away from the city. I had a 35 minute commute by train right to Manhattan. There are tons of such suburbs in Westchester, because they have train lines running through the whole area.
Meanwhile, my parents live in D.C. suburbs that are similarly priced, half the distance out of the city, but where the commuting options are a 1-1.5+ hour drive. In Westchester you've got a little downtown and can walk to shops and restaurants. In the D.C. suburbs you have to drive 20 minutes just to get to the drug store.
It's all about city design.
Metro Vancouver recently did a study comparing affordability combining both housing and transportation costs. Once transportation was considered, Vancouver City proper dropped to one of the 3 most affordable Metro Vancouver cities, whereas outlying suburbs rose to least affordable. The gap in transportation costs between the cheapest and most expensive areas was several thousand dollars a year, possibly as high as $12k a year.
http://www.metrovancouver.org/services/regional-planning/Pla...
What I was thinking when I when I wrote "I'm not sure anyone loves suburbia" was that I'm not sure anyone loves that big suburban commute to the city. If that's eliminated, or mitigated by excellent transit connections (ie. pre-automobile street car suburbs), then a lot of negatives go away.