There are a several cities I really regret not visiting, Veracruz and Morelia to name just two. Sometimes I've bypassed because of being too much in a rush. For example I had it in my mind to get to Cancun. In hindsight it's a government created resort with less in the way of Mexican cultural history when compared to some cities like Veracruz. I wish I had shaved a day off Cancun and added someplace else. Still, next time.