In Simcity Buildit I have noticed that the NPC city has larger buildings than I have in my own. What allows you to upgrade to those? I have many times had no buildings left to upgrade because all were upgraded to their max. None of my buildings would offer upgrades until I built new building.
This makes me think there are some factors of the game that control what upgrade level a building can be at max. I have upgraded roads connected to buildings and still do not ever get upgrade options for them (and even when I run out of buildings viable to upgrade.
I should also note that my level is greater than the NPC player (he has changed level a couple of times after I passed him, but typically seems to take a few levels before that happens)
Best Answer
In order to unlock the modern looking luxury skyscrapers, you need to have a sufficient amount of specialty services available for your sims. This includes (in addition to parks) schools, transportation, casinos, landmarks, etc.
You can determine which areas are candidates for the modern skyscrapers by clicking on the "Wealth Forecast" (looks like a hard hat icon) under the residential tab. The dark orange buildings will upgrade to Luxurious Homes.
If your current buildings haven't finished upgrading, by adding enough services to the area, they will become luxury buildings by the next upgrade. Otherwise, you have to demolish the old buildings and start over to get the luxury buildings.