Houston (#4) is the largest city that I have never been to. I have changed planes at both IAH and Hobby but I have never stepped out of the airport.
Spent a lot of time in NYC.
Spent one night in Los Angeles.
Grew up in Chicago.
Spent one night in Houston.
Been to Philadelphia on a number of occasions.
Changed plans in the Phoenix airport.
I guess it’s San Antonio.
Huh, I thought I replied to this.
The answer depends on how you define “city.” If you mean a municipal government’s boundaries, I have never been in Surrey, BC, which is a suburb of Vancouver.
If you mean a city, e.g. an urban agglomeration - most people would think of Surrey as being generally part of “Vancouver” - I believe it’s Sherbrooke, QC. I have been to almost all Canadian cities of any significant size, but not Sherbrooke.
I have not seen New York City. That is one place I have yet to visit.