I can think of quite a few... San Francisco, Seattle, Portland, Chicago, New York, Boston, Dallas, Austin, Houston. Even Los Angeles and Atlanta have nice "new downtown" areas, though the traditional downtowns are sketchy (Wilshire and Midtown, respectively).
Lots of cities have nice areas around downtown, but few have nice areas around downtown where you can do everything you need (walk to work, walk to the grocery, etc). They do exist, obviously, and some people are more tolerant about walking through a few bad blocks on the way to work than others, but it is my observation that most U.S. cities don't do a good job of making downtown a desirable place to live. Many U.S. downtowns essentially shutdown after 5pm as all of the restaurants close for the day and everyone commutes back to the 'burbs.
That's the traditional "business district" style downtown, yeah, but afaict there's been a shift away from that in the past 15-20 years, and now many people commute to downtown in the evenings, because that's where all the restaurants/bars/clubs/theaters are. That's definitely the case in the Bay Area, where SF is much more lively after 5pm than most of the Valley is (Santa Clara is basically dead once office workers go home). Was also the case in Midtown Atlanta when I lived there a few years ago; big influx from the suburbs in the evenings, esp on weekends.
SOMA too for the most part. Sadly the walk between workable parts (SOMA/FiDi) and livable parts has goes through areas that are less than ideal for walking (in terms of feeling safe).
Salt Lake City's downtown and everything north, east, and south isn't sketchy at all. If you start going west, it's a little different story but compared to most anywhere in SF it's super tame.
SLC blocks are huge, though, and (with exception of a thin strip along Main St), it was clearly not designed with walking in mind. Yes, there are sidewalks, but there's very little street furniture, retail is set far back and not at sidewalk level, and lights don't open for pedestrians unless you specifically press the button.
It's better than most, I agree, but still a far cry from NYC, Boston, or SF.
I got pulled over by the police for walking in Houston
Running alongside the freeway is an access road where all the on-off ramps feed. It has a wide sidewalk along the side and it was only a couple of junctions between the hotel and the site I was visiting so I walked.
A police car immediately pulled up to ask where I was going and why? Fortunately the English accent convinced them I was obviously merely some pinko-commie weirdo and not a threat to Houston society.
I could see that in the suburbs, but people commonly walk downtown, in the museum district, and the Rice area. Lots of new condo towers going up in the past few years, and the light rail connects those areas.
