There are a lot of different types of suburbs out there. I grew up in an old streetcar suburb in the Midwest where almost all of the kids walked to school (though most people still drove to work, since many jobs had sprawled out to office parks). I could walk to my job at a grocery store and there was a nice bike trail, and once I realized that biking was a practical form of transportation, in addition to recreation, the narrow side streets on the grid made for great biking even without any specific infrastructure. There are bars, restaurant, and a movie theaters, all within a quick walk.
But a lot of newer suburbs make it somewhere between unpleasant and dangerous to walk anywhere.
As a remark: Seattle has adopted a "mini-downtown" approach with desirable neighborhoods (that I hope gets copied elsewhere). Each neighborhood that starts seeing some density growth/interest has? will get pushed toward? having sort of a mini-city-center so that the neighborhood can kind of operate semi-independently within the city-umbrella. Kind of a federal/province approach within a city. I really appreciate it. I think that if a suburban town took this approach and drove towards growth in this fashion, it would be very pleasant to live.
Also - most post 1990s suburb growth doesn't use grids, so it becomes grievously difficult to easily walk/bike between areas, since it's never a straight line to achieve your goal.
We're a city of neighborhoods. The Loop is the main tourist destination, sure, but few people actually live there. We live in neighborhoods. Some have houses with (small) lots, some have apartments, some have both. There's a nice sprinkling of parks, and most neighborhoods have amenities like a few independent restaurants, maybe some chain restaurants, coffee shops, bars, CVS, and a grocery store or two. Things you might even find in a larger/denser suburb. The difference is that you can usually walk <15 minutes to a train that comes every <15 minutes to take you downtown.
Unlike Manhattan, buses are best for most short-haul trips while the rail system is best for longer rides (we don't do the "trains go north-south, buses go east-west" thing.)
Public transit is often slower than driving, even with traffic, but you can enjoy the time if you bring your smartphone and/or a book.
But a lot of newer suburbs make it somewhere between unpleasant and dangerous to walk anywhere.