better buildings, including cool scrapers are indeed created when city value increases, you can check the land value in the residential menu, 2nd tab
also if you want t o know if your building will be standard/premium or luxury you can check that also in the residential menu, 3rd tab
from personal experience before i upgrade a home, i check if it its luxury property, if it isnt, i move it in the city to a place where it becomes luxury and only then i upgrade it 😉 this has helped pop up some cool scrapers 😉
