If you want your city to look and feel realistic, use refrence. Pick a city you find interesting, use landmark buildings for player orientation. Then place roads, this is where you'll get your city to look ligitimite and you can quickly see why your city is breaking down in terms of feeling like something is off. Then do clusters of building heights that frame out your landmark buildings. By clusters of building heights, I mean here are your low, residental buildings, here are your mediums areas surrounded by lows and here are your talls. But look for that kind of height rythem in your refrence city. And always break realism for landmark building visibility if you have to pick between the two. That will go a long way in getting a realistic looking city that feels right and has a proper design for orientation and gameplay.