The city Los Angeles was the inspiration for "Paradise City", just happened to be where the band was living at the time.

Appetite for Destruction LP, Wikipedia

All about the rough life on the streets, but the chorus was based on Axl Rose's memories of living in the Midwest, visions of green grass, innocence and the possibilities of life.

Leave it to Slash who wanted the chorus to be: "Take me down to the Paradise City where the girls are fat and they got big t--ties."
Slash wasn't fond of the reference "Grass Is Green" in the song, but the band overruled his idea for a more radio-friendly verse.
This is the only track on 'Appetite For Destruction' with a prominent synthesizer. It was the idea of Axl Rose.

Guns and Roses perform, "Paradise City":