Cars 2 is my favourite of the 3 with how bonkers it is. Cars 3 was an expensive nap.
As for Monstropolis, wouldn't that just be a generic city with puns and slightly adjusted trim/awnings? I know everyone clamours for Monstropolis, yet the Monsters Inc queue is pretty bland and even the Monsters University Photo Op wasn't something I saw being a wildly immersive land. Not unless Disney was going to add AA/puppets from windows and gags to discover. But seeing how they designed GE and AC, I don't see them doing that.