Also, apparently there's an episode where Spacely and Cogswell are arguing about real estate and they discuss a rule of Orbit City which requires all buildings to be at least 2200 feet off the ground (I assume from their "bottom"), which would make their homes roughly the top floors of the Burj Khalifa
IIRC the canon reason they are above the clouds is because of smog.
Just searched, and it looks like you're correct.
Also, apparently there's an episode where Spacely and Cogswell are arguing about real estate and they discuss a rule of Orbit City which requires all buildings to be at least 2200 feet off the ground (I assume from their "bottom"), which would make their homes roughly the top floors of the Burj Khalifa